Condition Analysis
AI-powered assessment using site data and 14-day weather history
Corby's Crag is currently unsuitable for climbing due to repeated recent rainfall on already-saturated Fell Sandstone, with more rain forecast today and heavy rain (16.6mm) expected tomorrow. The sheltered, below-road-level position means moisture from the last week's accumulation (16.4mm in 7 days) has had almost no opportunity to clear, and conditions will only worsen over the coming days.
Based on weather conditions only — does not cover bird nesting restrictions or other access issues.
- Corby's below-road-level position channels runoff from above onto the rock face, meaning it can remain wet even when neighbouring crags have dried — check the crag top for dampness before ever committing.
- The rock here is notably more friable and porous than other Northumberland sandstone; after rain it develops 'scrittle' (loose surface grit) that persists even after the surface looks dry, requiring an extended dry spell to clear.
- The sheltered setting with minimal wind exposure dramatically slows evaporation — drying times here can be double or more compared to exposed Fell Sandstone crags.
- Soft Fell Sandstone is particularly vulnerable to top-rope damage; avoid top-roping entirely when conditions are anything less than thoroughly dry.
Warnings
3
- Climbing on wet Fell Sandstone causes permanent, irreversible damage to holds — the iron oxide cemented features that define Corby's routes cannot regenerate once broken.
- The rock surface may appear dry while remaining deeply saturated internally — do not be deceived by surface appearance at this crag given the recent rainfall pattern.
- Near-freezing overnight temperatures (-0.8°C on May 6th) combined with saturated rock create freeze-thaw damage risk that compounds structural weakening.
Reasoning
The rock is almost certainly saturated internally: 13.2mm fell on May 3rd, followed by only one fully dry day (May 4th and 6th), with light rain on May 5th and today (May 7th), and the 28-day total of 34.3mm on high-porosity sandstone in a sheltered position means deep moisture has had no chance to clear.
Despite some moderate winds (13–20 km/h), the sheltered below-road position negates much of this benefit; average humidity of 77% over the last week and persistent cloud cover have severely limited evaporation, and zero consecutive dry days confirms no meaningful drying window has occurred.
With the rock likely well above the critical 1% saturation threshold and repeated wetting cycles over the past month, hold breakage risk is high — the iron oxide cemented holds that define Corby's routes are especially vulnerable to grain loosening when wet.
Early May in Northumberland brings improving temperatures but the recent pattern of cool, humid, showery weather has prevented the spring drying that would normally be underway by now, and overnight lows near or below freezing (e.g. -0.8°C on May 6th) add marginal freeze-thaw concern on saturated rock.
Contributing Factors
7
13.2mm on May 3rd plus additional lighter rain on May 5th and today totals over 16mm in the last week, keeping the porous sandstone deeply saturated.
There has not been a single fully dry day since May 4th, giving the rock no sustained drying window.
The crag's sheltered, sunken position channels runoff from above and blocks wind-driven evaporation, dramatically extending drying times compared to exposed crags.
Average humidity of 77% over the past week severely limits evaporative drying, especially in the sheltered microclimate of the crag.
2mm forecast for May 8th followed by 16.6mm on May 9th will re-saturate any surface drying that occurs, resetting the drying clock entirely.
Average temperatures around 7.7°C over the past week provide only modest evaporative energy, and overnight lows near freezing add marginal freeze-thaw risk on saturated rock.
Light rain is forecast from late afternoon today (1.4mm total), adding fresh moisture to already-damp rock.
Recommendations
3
- Do not visit Corby's Crag in the coming days — the rock needs a sustained dry spell of at least 3–4 days with wind and low humidity before conditions could begin to improve.
- Monitor weather from May 12th onwards; if the forecast dries out after that date, the earliest realistic assessment window would be around May 15–16 at the earliest.
- If desperate to climb this week, consider non-porous alternatives such as whinstone crags (e.g. Kyloe or the Great Whin Sill venues) which are structurally unaffected by moisture, though surface grip will still be reduced.
Previous Analyses
Do Not Climb
45%
2 days ago
Despite a dry day today with low humidity, Corby's Crag received 1.3mm rain only yesterday (May 5th) and 13.2mm on May 3rd, and its sheltered below-road-level position means drying has been very slow — the rock is almost certainly still holding significant internal moisture. With heavy rain forecast from May 8th onwards (60mm+ over three days), conditions are deteriorating rather than improving.
Based on weather conditions only — does not cover bird nesting restrictions or other access issues.
- Corby's below-road-level position channels runoff from the road and surrounding ground onto the rock face, meaning it can remain wet even when nearby crags have dried.
- The crag's known 'scrittle' problem — loose grit on holds after rain — indicates the friable sandstone here is more porous than typical Fell Sandstone, requiring extended drying beyond standard guidelines.
- The sheltered setting with minimal wind penetration dramatically slows evaporation; today's SE breeze at 16 km/h will have limited effect in the sheltered hollow.
- The NW-facing sections will have received almost no direct sun for drying, while south-facing sections may appear superficially dry but could still be saturated internally after the recent wet spell.
Warnings
3
- Freeze-thaw cycling is active — overnight frost on moisture-laden Fell Sandstone causes cumulative structural damage and increases hold breakage risk.
- The upcoming 60mm+ rainfall event (May 8–10) will fully re-saturate the rock; do not attempt to climb in a narrow window before this arrives.
- Corby's 'scrittle' phenomenon means holds may feel deceptively grippy on the surface while the underlying rock is critically weakened — surface appearance is unreliable here.
Reasoning
The crag received 13.2mm on May 3rd and 1.3mm on May 5th, with only one full dry day (today) since the last rain, and the sheltered position and high average humidity (78% over the past week) mean internal moisture levels are almost certainly still elevated.
With only ~24 hours of dry weather since the last rain, temperatures around 8°C, and the crag's sheltered aspect limiting wind exposure, drying has been grossly insufficient — Fell Sandstone guidance calls for 48–72+ hours of dry weather after heavy rain, and this site's known slow-drying characteristics demand even longer.
The rock is described as more friable and porous than typical Northumberland sandstone, and with likely internal saturation from the recent 15mm in 7 days, there is a genuine risk of hold breakage and the characteristic 'scrittle' problem on climbing holds.
Early May in Northumberland with overnight frost (down to -1.3°C last night) means freeze-thaw cycling on potentially saturated rock is an active concern, compounding structural weakening from moisture.
Contributing Factors
7
13.2mm fell on May 3rd followed by 1.3mm on May 5th, giving a 7-day total of 15mm with only one dry day since the last precipitation.
Only one full dry day has elapsed since last rain, far short of the 48–72+ hours needed for this particularly porous and slow-drying crag.
The crag sits in a sheltered hollow below road level, severely limiting wind exposure and trapping humid air, which dramatically slows evaporation.
The below-road-level position means surface water drains onto the crag face, adding moisture beyond what direct rainfall deposits.
Afternoon humidity drops to 42–46% with moderate SE wind and clear skies, providing the best drying conditions seen in over a week.
Temperatures dropped to -1.3°C overnight, creating freeze-thaw stress on rock that likely remains above the 60% critical saturation threshold.
The forecast shows 7.8mm on May 8th, 20.6mm on May 9th, and 33.3mm on May 10th — any drying progress will be completely reversed.
Recommendations
3
- Do not climb today — the rock has had insufficient drying time since 13.2mm on May 3rd and 1.3mm yesterday, and internal moisture is almost certainly still present.
- With 60mm+ of rain forecast May 8–10, conditions will not be suitable for at least a week beyond that; monitor weather closely and wait for a sustained dry spell of 3–5 days minimum.
- If visiting the area, consider non-porous alternatives such as whinstone crags (e.g. Kyloe, Great Wanney) which are far more tolerant of recent rain.
Do Not Climb
85%
3 days ago
Corby's Crag received 13.2mm of heavy rain on May 3rd followed by light rain today (1.0mm), with only one dry day in between. Given the crag's sheltered, below-road-level position that channels runoff onto the face, and persistently high humidity averaging 80% over the past week, the rock will be saturated internally despite any surface drying.
Based on weather conditions only — does not cover bird nesting restrictions or other access issues.
- Corby's below-road-level position channels runoff from the road and surrounding ground onto the rock face, meaning the 13.2mm on May 3rd likely delivered even more water to the cliff than open-aspect crags received.
- The crag's sheltered position means wind assistance for drying is minimal despite moderate regional winds — still air at the rock face prolongs moisture retention significantly.
- The known 'scrittle' phenomenon at Corby's (loose grit forming on holds after rain) indicates the rock is particularly friable and porous; even when the surface looks dry, holds may be structurally compromised.
- The south-facing sections will dry faster than the NW-facing sections, but given the runoff issue and sheltered setting, even the south face needs extended dry time after this much rain.
Warnings
3
- Freeze-thaw damage risk is elevated with overnight temperatures near 0°C on saturated rock — climbing on weakened holds could cause breakage and permanent route damage.
- The rock surface may appear dry before the interior has dried — do not be deceived by surface conditions at this crag given its known porosity and runoff issues.
- Fell Sandstone that has been through repeated wetting cycles (as in this 28-day period) can remain structurally weakened for an extended period even after the surface dries.
Reasoning
The 13.2mm deluge on May 3rd followed by today's 1.0mm means the rock is almost certainly saturated internally, especially given only one intervening dry day and the crag's runoff-channelling topography.
With the sheltered position limiting effective wind drying, high average humidity (80% over the past week), and cool temperatures (average 7.9°C), meaningful drying since the May 3rd rain has been negligible — the single dry day on May 4th was insufficient for a crag that needs 48-72+ hours of good drying conditions after heavy rain.
Fell Sandstone loses up to 50% of compressive strength when wet, and Corby's is noted as more friable and porous than most Northumberland sandstone — climbing now risks hold breakage and permanent route damage.
Early May in Northumberland with overnight temperatures dropping near or below freezing (min -1.0°C forecast tomorrow) creates potential freeze-thaw risk on saturated rock, compounding structural concerns.
Contributing Factors
8
13.2mm fell on May 3rd — well above the 10mm threshold requiring 48-72+ hours of dry weather — followed by additional 1.0mm today.
Only one dry day (May 4th) has elapsed since the heavy rain, far short of the minimum 48-72 hours needed, and today brought more rain.
The crag's sheltered, below-road-level setting channels runoff onto the face and limits wind-assisted drying, making it one of the slowest-drying Northumberland crags.
Average humidity of 80% over the past week severely limits evaporative drying, especially in the sheltered microclimate at the crag.
Average temperature of 7.9°C over the past week and today's max of only 8.3°C provide limited thermal energy for evaporation.
Overnight temperatures near or below 0°C (min -1.3°C forecast tomorrow) on saturated rock create active freeze-thaw damage risk above the 60% saturation threshold.
32.6mm over the past 28 days with frequent small rain events means the rock has had no opportunity to fully dry out at depth.
No precipitation is forecast for the next 6 days, which will allow progressive drying if humidity drops.
Recommendations
3
- Do not climb at Corby's today or for at least the next 2-3 days; the rock needs a sustained dry spell to recover from the May 3rd heavy rain and today's additional moisture.
- Before visiting later this week, check the ground at the base of the crag and the crag top for dampness — if either is moist, the rock is still wet internally.
- If conditions improve by mid-week, prioritise the south-facing sections and test holds carefully for the 'scrittle' (loose surface grit) that Corby's is known for after wet periods.
Do Not Climb
88%
4 days ago
Corby's Crag received 13.2mm of heavy rain yesterday (May 3rd) in near-saturated conditions, with only one dry day elapsed since. Given the crag's sheltered position, below-road-level runoff channelling, and notably friable/porous rock, the sandstone will be thoroughly saturated internally despite any surface drying today.
Based on weather conditions only — does not cover bird nesting restrictions or other access issues.
- Corby's below-road-level position channels runoff from the road and surrounding ground onto the rock face, meaning it received significantly more water than the 13.2mm headline figure suggests.
- The crag's sheltered position with light winds (currently only ~10-15 km/h) dramatically slows evaporation; the overnight humidity was 93-94% providing essentially zero drying overnight.
- The rock at Corby's is described as more friable and porous than typical Northumberland sandstone, and develops 'scrittle' (loose grit) on holds after rain — this hazard persists even after the surface appears dry and requires a prolonged dry spell to clear.
- South-facing sections may appear deceptively dry on the surface by afternoon today while the interior remains fully saturated — the NW-facing sections will be visibly wet.
Warnings
3
- Climbing on saturated Fell Sandstone causes permanent, irreversible damage to holds and routes — Corby's friable rock is especially vulnerable.
- The rock surface may appear dry by this afternoon while remaining fully saturated internally — do not be deceived by surface appearance.
- Further rain is forecast for tomorrow (3.8mm on May 5th) which will reset the drying clock before any meaningful drying has occurred.
Reasoning
The rock is almost certainly saturated internally after 13.2mm of sustained rain over 12+ hours yesterday in near-100% humidity conditions, compounded by additional smaller rain events on April 21st, 26th-28th, and May 2nd that kept the rock from ever fully drying out.
Only one dry day has elapsed since heavy rain, with overnight humidity at 93-94% and very light winds (2-6 km/h) providing negligible drying; even today's improving afternoon conditions (humidity dropping to ~50%, moderate breeze) are far from sufficient for this sheltered crag — a minimum of 48-72+ hours of dry weather is needed.
The rock is at high risk of hold breakage and grain loosening given likely saturation levels well above the critical threshold; Corby's notably friable sandstone makes this even more dangerous than at other Fell Sandstone venues.
Early May in Northumberland provides moderate temperatures (~8-14°C) and lengthening days which aid drying, but the recent wet spell and high background humidity (81% average over the last week) mean seasonal conditions are only marginally helpful.
Contributing Factors
7
13.2mm fell over 12+ hours on May 3rd in near-saturated atmospheric conditions, thoroughly wetting the rock and surrounding ground.
After heavy rain on porous Fell Sandstone, a minimum of 48-72+ hours of dry weather is required, and only ~18 hours of drying have occurred so far.
Corby's sheltered, below-road-level setting experiences reduced airflow and overnight humidity remained above 90%, providing almost no evaporative drying.
The below-road-level position means additional water runs down onto the rock face from the road and surrounding saturated ground, increasing total moisture loading beyond rainfall alone.
31.6mm over the last 28 days with frequent small rain events means the rock has had no extended dry period to fully dry out internally.
Humidity drops to ~46-51% with temps reaching 13.7°C this afternoon, but this is far too short a window to meaningfully dry saturated sandstone.
Corby's rock is more porous and friable than typical Fell Sandstone, developing loose grit on holds after rain that persists even when the surface looks dry.
Recommendations
3
- Do not climb at Corby's Crag today — the rock is almost certainly saturated after yesterday's 13.2mm of rain and needs at least 2-3 more dry days to begin drying properly.
- If visiting later this week, check the crag top and base for dampness before committing; remember that surface-dry rock can still be dangerously wet internally at this venue.
- Consider visiting a non-porous alternative such as a whinstone crag if you need to climb today.
Do Not Climb
95%
4 days ago
Corby's Crag received 13.9mm of heavy rain today with 96% humidity, thoroughly saturating this already moisture-prone sandstone. The sheltered, below-road-level position and high porosity mean this crag will need several days of dry, warm weather before conditions are suitable for climbing.
Based on weather conditions only — does not cover bird nesting restrictions or other access issues.
- Corby's below-road-level position channels runoff from above directly onto the rock face, meaning it receives significantly more water than the rainfall figure alone suggests — after 13.9mm today, runoff loading will be substantial.
- The crag's known tendency to develop 'scrittle' (loose grit and dust) on holds after rain makes conditions dangerous even once the surface appears dry — a prolonged dry spell is needed to clear this.
- The sheltered aspect with low wind exposure (only 18.4 km/h today from NE) traps moist air against the rock, dramatically slowing evaporation compared to exposed Northumberland crags.
- The south-facing sections may begin to dry first in coming days, but NW-facing sections will retain moisture much longer — the crag should not be considered dry until all aspects have cleared.
Warnings
3
- Climbing on saturated Fell Sandstone causes permanent, irreversible damage to holds and routes — this is especially true at Corby's with its notably friable rock.
- Surface-dry appearance is deceptive at this crag; the below-road runoff means internal saturation persists long after the surface looks climbable.
- The NMC 'Love the rocks' ethic explicitly requires climbers to avoid wet sandstone — please respect this to preserve routes for future generations.
Reasoning
With 13.9mm of rain today at 96% humidity on top of intermittent precipitation throughout the past two weeks (14.7mm in the last 7 days), the rock is almost certainly fully saturated, particularly given the below-road-level runoff channelling.
The sheltered position, light winds (12–19 km/h recent average), and persistently high humidity (81% average over 7 days) severely limit drying; even with the forecasted dry day tomorrow, meaningful internal drying of this porous sandstone will take at minimum 48–72 hours under these conditions.
At near-full saturation, Fell Sandstone loses 10–50% of its compressive strength, and Corby's particularly friable and porous rock is at high risk of hold breakage and surface damage — climbing today or in the next 1–2 days would risk permanent route damage.
Early May temperatures averaging 8°C are marginal for effective drying, though overnight frost risk is diminishing; the recent pattern of cool, humid weather with frequent light precipitation has kept background moisture levels elevated throughout April.
Contributing Factors
7
13.9mm of rain today is well above the heavy rain threshold, requiring 48–72+ hours of dry weather for adequate drying on porous sandstone.
96% humidity today means virtually no evaporation is occurring, and the rock will remain saturated throughout the day.
The below-road-level, sheltered setting traps moist air, channels runoff onto the face, and dramatically slows drying compared to exposed crags.
14.7mm over the past 7 days and 33.8mm over 28 days with average humidity of 81% means the rock had limited opportunity to dry before today's heavy rain.
Winds of 12–19 km/h in a sheltered position provide minimal airflow across the rock surface, further impeding drying.
Average temperatures around 8°C over the last week provide limited thermal energy for evaporation, prolonging drying times.
Corby's sandstone is noted as more friable and porous than typical Northumberland sandstone, making it more vulnerable to moisture damage and 'scrittle' formation.
Recommendations
3
- Do not climb at Corby's Crag today — the rock is saturated and at high risk of damage and hold breakage.
- Wait for a minimum of 3 consecutive dry days with low humidity before considering a visit; check the crag top and base for dampness before committing.
- If conditions improve later in the week, inspect the south-facing sections first as they will dry fastest, but be vigilant for 'scrittle' on holds which indicates the rock has not fully dried internally.
Do Not Climb
95%
4 days ago
Corby's Crag received 16.7mm of heavy rain today with 97% humidity, thoroughly saturating this already moisture-prone Fell Sandstone. The sheltered, below-road-level position and persistent high humidity over recent weeks mean the rock will need several days of dry weather before conditions are suitable for climbing.
Based on weather conditions only — does not cover bird nesting restrictions or other access issues.
- Corby's below-road-level position channels runoff from the road and hillside above directly onto the rock face, meaning it receives significantly more water than the rainfall figure alone suggests.
- The crag is known for developing 'scrittle' — loose grit and dust on holds — after rain, which persists even after the surface appears dry and indicates ongoing internal moisture migration.
- The sheltered aspect means very little wind reaches the rock face despite moderate winds in the wider area, dramatically slowing evaporative drying.
- The NW-facing sections will be particularly slow to dry given limited direct sun; even the S-facing sections are compromised by the below-road-level setting and surrounding shelter.
Warnings
3
- 16.7mm of rain today has fully saturated this particularly friable and porous Fell Sandstone — climbing now risks irreversible hold breakage and route damage.
- Surface-dry appearance can be deeply misleading at Corby's; the below-road runoff means internal saturation persists long after the surface looks climbable.
- Overnight temperatures near freezing combined with saturated rock create freeze-thaw damage risk over the coming nights.
Reasoning
With 16.7mm falling today at 97% humidity on top of an already damp period (17.5mm in the last 7 days, average humidity 81%), the rock is almost certainly fully saturated throughout, well above the critical thresholds for strength loss and freeze-thaw vulnerability.
The sheltered position negates much of the forecast wind benefit, and with humidity at 80% forecast for tomorrow and recent weeks consistently around 78–84%, effective drying will be very slow — realistically requiring 3–4 days of genuinely dry weather with lower humidity before the interior approaches safe moisture levels.
At full saturation the rock will have lost 30%+ of its compressive strength; the particularly friable nature of Corby's sandstone and the runoff-channelling position make hold breakage and surface damage a serious risk if climbed on now.
Early May in Northumberland with overnight temperatures still dipping near or below freezing (min -0.4°C on April 29th, -1.0°C on April 24th) means freeze-thaw cycling remains a concern on saturated rock, though the immediate forecast shows milder minimums.
Contributing Factors
7
16.7mm of rain today is the heaviest single-day total in the entire 28-day record, delivering a thorough soaking to an already moisture-laden crag.
At 97% relative humidity, essentially no evaporative drying is occurring from the rock surface today.
The last 28 days have seen 36.6mm of rain with average humidity around 78–84%, meaning the rock has had no opportunity to fully dry out before today's deluge.
The sheltered, sunken position blocks wind from reaching the rock face and channels additional runoff from the road above, compounding the moisture problem well beyond what weather station data suggests.
Forecast winds of 12–24 km/h are moderate but will be substantially attenuated at the sheltered crag face, offering limited drying assistance.
From May 6th onwards, three consecutive dry days with dropping humidity (63–66%) and moderate wind offer the first real drying window, though the crag's shelter will delay the benefit.
Corby's notorious post-rain 'scrittle' means even once the surface looks dry, loose grains on holds will compromise friction and indicate ongoing internal moisture migration.
Recommendations
3
- Do not climb at Corby's today or for at least the next 2–3 days; the rock is thoroughly saturated and any climbing risks permanent hold damage and personal injury.
- When returning after the drying window, check the crag top and base of routes for dampness before committing — if the ground at the base is still moist, the rock is not ready.
- Consider alternative non-porous venues in the region (e.g. Whinstone crags like Crag Lough or Great Wanney's harder routes on whinstone) if you need to climb this week.
Do Not Climb
95%
4 days ago
Corby's Crag received 15.9mm of heavy rain today with 97% humidity, and the rock is certainly saturated. The sheltered, below-road-level position and high porosity of this particularly friable Fell Sandstone mean it will need several days of dry weather before conditions are suitable for climbing.
Based on weather conditions only — does not cover bird nesting restrictions or other access issues.
- Corby's below-road-level position channels runoff from the road and surrounding ground onto the rock face, meaning it receives more water than open-aspect crags and will be exceptionally wet after today's 15.9mm.
- The rock here is notably more friable and porous than other Northumberland sandstone, and develops a loose 'scrittle' layer on holds after rain that persists even when the surface looks dry — this is a serious grip and rock-damage hazard.
- The sheltered setting with minimal wind exposure means drying is significantly slower than at exposed crags; the 12–18 km/h winds forecast over the next few days will barely penetrate to the rock face.
- The south-facing sections will benefit from any sunshine over the coming days, but the NW-facing sections will remain damp much longer — assess both aspects independently before climbing.
Warnings
3
- 15.9mm of rain today has deeply saturated this particularly porous and friable sandstone — climbing now would risk serious hold breakage and permanent route damage.
- The surface may appear dry within a day or two but interior saturation and the 'scrittle' layer will persist much longer at this sheltered crag — do not be deceived by surface appearance.
- Check BMC RAD for any bird nesting restrictions at Corby's Crag, as peregrine/raven restrictions may be active through June.
Reasoning
The rock is fully saturated after 15.9mm of rain today at 97% humidity, with additional runoff channelled from the road above — internal moisture levels will be very high throughout the crag.
Drying will be very slow given the sheltered position, moderate humidity (80% forecast tomorrow), and light-to-moderate winds that won't effectively reach this below-road-level crag; even the south-facing sections need 48–72+ hours minimum.
Compressive strength is severely reduced in this particularly porous and friable sandstone; climbing now risks hold breakage, surface grain loosening, and the characteristic 'scrittle' problem that makes holds unreliable and damages the rock.
Spring conditions in late April/early May are improving but the preceding weeks have been persistently damp (35.8mm over 28 days, average humidity 81%), meaning background moisture levels in the rock were already elevated before today's heavy rain.
Contributing Factors
6
15.9mm of rain today is a significant soaking event for porous Fell Sandstone, requiring 48–72+ hours of dry weather to recover.
Today's 97% humidity and a weekly average of 81% mean virtually no evaporative drying is occurring and the rock is deeply saturated.
The below-road-level, sheltered setting traps moisture, channels runoff onto the face, and prevents wind from aiding drying.
This crag's sandstone is noted as more friable and porous than typical Northumberland sandstone, making it exceptionally vulnerable to moisture damage and the 'scrittle' problem.
The past 28 days have seen 35.8mm of rain with consistently high humidity (averaging ~80%), so the rock had elevated background moisture before today's heavy rain.
After tomorrow's dry day and a small shower on May 5th, a sustained dry spell with dropping humidity (63–66%) is forecast from May 6th onwards.
Recommendations
3
- Do not visit Corby's Crag today or tomorrow — the rock is saturated and climbing would risk permanent damage to holds and routes.
- Wait until at least May 7th or 8th, then check the crag top and base for dampness before committing; if the ground at the base is still moist, the rock is still too wet internally.
- When conditions do improve, avoid top-roping (which causes disproportionate damage to soft Fell Sandstone) and brush holds gently with a soft boar's hair brush only.
Do Not Climb
55%
5 days ago
Despite a relatively dry spell from April 22–May 1, persistent high humidity (averaging 79%), light but frequent drizzle/trace precipitation, sheltered aspect, and today's 0.4mm rain mean Corby's Crag is unlikely to have fully dried internally. With 10mm of rain forecast tomorrow, conditions are about to deteriorate significantly — today is marginal at best and climbing is not recommended.
Based on weather conditions only — does not cover bird nesting restrictions or other access issues.
- Corby's below-road-level position channels runoff from the road and hillside above onto the rock face, meaning it receives more moisture than rainfall alone would suggest — even trace precipitation can contribute meaningful wetting.
- The crag's known tendency to develop 'scrittle' (loose grit on holds) after damp periods is a particular concern given the prolonged high-humidity spell; even if the surface appears dry, friable material may be present and dangerous.
- The sheltered position with light winds (averaging ~15 km/h from variable directions over the past week) dramatically slows evaporation compared to exposed Northumberland crags — drying times here can be double or more.
- The NW-facing sections will have received almost no direct sun during the recent easterly/SE wind pattern and will be the last to dry; south-facing sections are more promising but still subject to the same runoff and humidity issues.
Warnings
3
- Heavy rain (10mm) is forecast for May 3 followed by further rain May 5–6; do not plan climbing at Corby's for at least 48–72 hours after the last rain event.
- The rock's friable nature means holds may break even when the surface appears dry if internal moisture persists — exercise extreme caution and respect the NMC's 'Love the rocks' ethic.
- Check BMC RAD for any active bird nesting restrictions at Corby's Crag during the spring nesting season (February–June).
Reasoning
The rock has had only trace precipitation in the last 10 days but persistent humidity around 78–84% in a sheltered setting means evaporative drying has been extremely slow, and today's 0.4mm adds fresh surface moisture.
Light winds averaging 12–16 km/h at a sheltered crag with 75–84% humidity provide minimal drying potential; the south-facing sections may have surface-dried in the warmer spell (May 1 reached 18°C) but internal moisture likely persists given the crag's high porosity and friable nature.
The notably friable and porous rock at Corby's is at elevated risk of hold breakage and scrittle formation given weeks of intermittent dampness and high humidity, even though individual rainfall totals have been small.
Early May in Northumberland is a transitional period with improving temperatures but still-cool nights (sub-zero on April 24 and 29), and the forecast shows a return to unsettled weather from tomorrow — the brief drying window is closing.
Contributing Factors
8
Although individual totals were small, frequent trace-to-light precipitation on 7 of the last 14 days (plus 7.9mm on April 15) has kept the rock intermittently wetted, preventing a proper sustained dry-out.
Humidity has averaged 79% over the past week with no day below 69%, severely limiting evaporative drying especially at this sheltered crag.
The below-road-level sheltered setting receives runoff from above and experiences minimal wind-assisted drying, making it one of the slowest-drying crags in Northumberland.
Today's 0.4mm precipitation has added fresh surface moisture, resetting any surface drying progress.
Temperatures of 10–18°C over recent days provide some drying potential, but this is offset by high humidity and shelter.
Tomorrow's forecast of 10mm rain at 94% humidity will thoroughly saturate the crag, making any remaining drying progress irrelevant.
Winds have been light (12–16 km/h) and from variable directions over the past week, providing little effective drying at this already-sheltered venue.
The south-facing aspect received direct sun during the warmer days (May 1 at 18°C), and these sections will be in the best condition if any climbing is viable.
Recommendations
3
- Do not climb today — the combination of persistent humidity, today's light rain, and the crag's slow-drying characteristics mean internal moisture is very likely still present.
- With 10mm forecast tomorrow and further rain on May 5–6, the next realistic climbing window at Corby's is not before May 8–9 at the earliest, assuming dry weather holds.
- If visiting later in the week, test the crag top and base for dampness before committing; check for scrittle on holds by gently brushing key holds and assessing grain looseness.
Marginal — Assess Conditions
55%
6 days ago
Three consecutive dry days culminating in today's warm 17.7°C and lower humidity (67%) have likely dried south-facing sections, but the sheltered, below-road-level position and persistently high humidity over the past week (averaging 80%) mean NW-facing sections and the crag base may still hold internal moisture. A careful on-site assessment is essential before climbing.
Based on weather conditions only — does not cover bird nesting restrictions or other access issues.
- Corby's below-road-level position channels runoff from above onto the rock face, meaning even light rain on the road and hillside above can wet the crag disproportionately — check the crag top for dampness before committing.
- The crag is known to develop 'scrittle' (loose grit on holds) after rain as the soft, friable Fell Sandstone dries unevenly — feel for gritty texture on holds even if they look dry.
- The sheltered aspect traps still air and slows evaporation, but on warm sunny days like today (17.7°C, southerly breeze) the south-facing sections can warm up significantly and dry faster than expected.
- Multiple small rain events through mid-to-late April (7.9mm on the 15th, plus frequent trace amounts) have kept the rock periodically re-wetted, preventing a deep cumulative dry-out despite no single deluge.
Warnings
2
- Do not assume the rock is dry based on surface appearance alone — Fell Sandstone can appear dry while remaining saturated internally, and Corby's friable stone is especially prone to hidden moisture damage.
- Rain forecast for May 3rd (3.1mm, 94% humidity) will reset drying progress; if you don't climb today or tomorrow, expect to wait several more days.
Reasoning
The last significant rain was 1.4mm on April 21st, with only trace amounts (0.1–0.2mm) since; three fully dry days have followed, but persistently high humidity (~80%) and the sheltered position limit how much internal moisture has been driven off.
Today's warm southerly conditions (17.7°C, 67% humidity) are the best drying conditions in over a week, and south-facing sections will have benefited substantially, but the NW-facing rock in a sheltered hollow with light winds receives limited direct sun and airflow, making 3 days marginal for full drying.
The friable, high-porosity Fell Sandstone at Corby's is more susceptible to hold breakage than typical Northumberland sandstone; the repeated wetting-drying cycles through April and residual internal moisture elevate the risk of grain loosening and scrittle.
Early May in Northumberland is transitional — day temperatures are improving but overnight lows near or below freezing (−1.0°C on April 24th, −0.4°C on April 29th) have slowed overnight drying and created minor freeze-thaw stress on any residually damp rock.
Contributing Factors
8
No measurable rain since April 28th (0.2mm trace), giving three full dry days which is approaching the minimum community standard for porous rock.
17.7°C with 67% humidity and a southerly breeze represent the best drying conditions in over two weeks, accelerating surface and near-surface evaporation.
The crag sits below road level in a sheltered hollow, severely limiting wind-driven evaporation and trapping humid air against the rock.
Average humidity over the past week was 80%, significantly limiting net evaporation rates even on nominally dry days.
25.4mm over 28 days with frequent small re-wetting events (including 7.9mm on April 15th) prevented the rock from ever fully drying out during April.
South-facing sections receive direct sun and will have dried significantly faster, while NW-facing sections remain shaded and will retain moisture much longer.
Overnight lows of −1.0°C (April 24th) and −0.4°C (April 29th) following wet periods create freeze-thaw stress on any residually saturated rock.
Corby's sandstone is notably more friable and porous than other Northumberland crags, and the repeated wetting cycles increase the likelihood of loose surface grit on holds.
Recommendations
3
- Perform a thorough hands-on assessment: check the crag top for dampness, feel holds for scrittle (loose grit), and test the ground at the base — if it's still moist, the rock likely is too.
- Prioritise south-facing routes only; avoid NW-facing lines which will have had far less drying benefit from today's sun and warmth.
- Avoid top-roping entirely — Corby's soft Fell Sandstone is particularly susceptible to top-rope damage, and any residual internal moisture compounds this risk.
Do Not Climb
55%
9 days ago
Despite only trace precipitation in the last week, the persistent high humidity (81% average), sheltered position, and below-road-level drainage at Corby's Crag mean internal moisture is likely still present. The cumulative 28mm over the past month, combined with cool temperatures and very high overnight humidity (reaching 96%), has not allowed this notably porous and friable sandstone adequate drying conditions.
Based on weather conditions only — does not cover bird nesting restrictions or other access issues.
- Corby's below-road-level position channels runoff from the road and hillside above onto the rock face, meaning the crag can receive moisture even from very light rain events that wouldn't affect other crags.
- The crag is known to develop 'scrittle' — loose grit on holds — after damp periods, which can persist even when the surface appears dry and requires prolonged dry, windy weather to clear.
- South-facing sections will be drying faster than NW-facing sections; the NW aspect areas are likely still holding significant internal moisture given the cool, humid week.
- The sheltered, below-road setting traps humid air against the rock, and overnight humidity has been consistently above 90%, effectively halting evaporation for 10–12 hours each night.
Warnings
2
- Overnight frost (min -0.1°C today) combined with possible residual internal moisture creates freeze-thaw damage risk — climbing on subtly damp rock in these conditions can cause permanent hold breakage.
- The 'scrittle' phenomenon at Corby's means surface-dry rock can still be structurally compromised; do not trust surface appearance alone at this crag.
Reasoning
Although only 0.4mm fell in the last 7 days, the preceding weeks saw 28mm total, and the persistently high humidity (81% average, overnight peaks to 96%) at this sheltered crag means internal moisture is unlikely to have fully dissipated from this notably porous and friable Fell Sandstone.
Light winds (averaging ~14 km/h from variable directions) and the sheltered below-road position severely limit air movement across the rock face, while cool temperatures (6.5°C average) and high humidity mean drying has been extremely slow — likely insufficient even after several nominally dry days.
Corby's sandstone is described as more friable and porous than typical Northumberland Fell Sandstone, and any residual internal moisture significantly increases the risk of hold breakage and surface grain loosening, especially under the stress of climbing.
Late April conditions in Northumberland are still marginal for sandstone — overnight temperatures dropping near or below 0°C (as on April 24 and today) combined with potential internal moisture create ongoing freeze-thaw risk, and spring drying has been hampered by consistently damp air masses.
Contributing Factors
7
Only 0.4mm of rain in the past 7 days, with the last significant rain (7.9mm) falling on April 15, giving a reasonable window for drying.
Average humidity of 81% over the last week, with overnight values consistently above 90%, severely limits net evaporation from the rock even during nominally dry days.
The below-road-level, sheltered position traps moist air, channels runoff onto the face, and prevents the wind-assisted drying that more exposed crags would benefit from.
Average temperatures of only 6.5°C with overnight lows near or below 0°C slow evaporation significantly and introduce freeze-thaw risk to any internally damp rock.
Winds have been light (12–16 km/h) and from variable directions, and the sheltered crag position means effective wind at the rock face is likely even lower than reported.
28mm over the past 28 days represents a significant moisture load for this porous sandstone, and the lack of any sustained warm, dry, windy spell means deep moisture may persist.
Corby's is noted as more friable and porous than typical Fell Sandstone, meaning it absorbs water faster, takes longer to dry, and is more vulnerable to damage when damp.
Recommendations
3
- Wait for the forecast dry, warmer spell on May 1 (16°C, lower humidity) combined with stronger winds on April 30, then reassess — conditions may improve to climbable by May 1–2 if humidity drops as forecast.
- If visiting, check the crag top and base for dampness before committing; if the ground at the base is moist or holds feel gritty with 'scrittle', the rock is not ready.
- Focus attention on the south-facing sections which will have dried fastest, and avoid NW-facing routes which will be the last to dry out.
Climbing Outlook