Condition Analysis
AI-powered assessment using site data and 14-day weather history
Wavelength Boulders are currently saturated and actively wet after prolonged heavy rainfall through the winter. With 8mm of rain today, 96% humidity, zero consecutive dry days, and over 300mm in the last 28 days, the rock will be thoroughly wet and dangerously slippery — conditions are clearly unsuitable for climbing.
Based on weather conditions only — does not cover bird nesting restrictions or other access issues.
- The 15–20 minute uphill approach means conditions at the boulders may differ from the road — seepage from the saturated hillside above can keep the base and lower faces wet long after rain stops.
- The south-facing aspect is advantageous for drying in theory, but February daylight hours and persistent cloud cover across Snowdonia severely limit effective solar drying at 300m altitude.
- The stratified formations characteristic of these boulders can trap and channel water along horizontal breaks, creating persistent seepage lines that take longer to dry than open faces.
- At 300m with overnight lows near freezing in the coming days, any residual moisture could form verglas on the rock surface, creating an invisible and extremely dangerous slipping hazard.
Warnings
3
- Wet rhyolite is extremely slippery — attempting to climb on saturated boulders at 300m altitude in winter creates a serious injury risk.
- Near-freezing overnight temperatures forecast for late this week could produce verglas (thin ice) on rock surfaces, which may be invisible and extremely dangerous.
- The saturated hillside approach will be muddy and slippery — take care even if just walking in the area.
Reasoning
The rock is currently wet: 8mm of rain fell today with 96% humidity, there are zero consecutive dry days, and 66.6mm has fallen in the last 7 days alone on already saturated ground.
Despite moderate southerly winds (32 km/h), the near-saturated humidity (96%) and persistent cloud cover mean virtually no effective evaporative drying is occurring — the south-facing aspect provides negligible benefit under these conditions.
Rhyolite is non-porous and does not suffer structural weakening when wet, so hold breakage is not a concern; the risk here is entirely from slippery wet surfaces and loss of friction.
Mid-winter in Snowdonia brings short days, low sun angles, persistent cloud, and saturated ground conditions — this is the worst time of year for drying at 300m altitude, and the relentless rainfall pattern shows no sign of breaking.
Contributing Factors
6
304.6mm over 28 days with 8mm today and zero dry days — the site is thoroughly soaked with no meaningful drying window.
Average humidity of 93% over the past week with 96% today means evaporation is essentially negligible and the rock cannot shed surface moisture.
There has not been a single fully dry day recently, preventing any cumulative drying effect on the rock surface.
The south-facing aspect would normally aid drying, but low February sun angle, short days, and persistent overcast conditions render this advantage largely ineffective.
Winds of 32 km/h provide some airflow but cannot drive meaningful drying when the air itself is near saturation at 96% humidity.
The next 6 days forecast 115.4mm of additional rain including a massive 55.4mm on March 1st, meaning conditions will only deteriorate further.
Recommendations
3
- Do not visit for climbing today — the rock will be wet and dangerously slippery; consider indoor alternatives in the Llanberis area.
- Monitor the forecast for a window of at least 2 consecutive dry days with humidity below 80% before making the uphill approach.
- If you do visit the Pass, use the time to scout approach paths and identify which boulders and faces might dry fastest for a future session.
Analysis Calendar
February 2026
AI Analysis Context
System Prompt
You are an expert geologist and experienced rock climber specialising in UK climbing sites across Northern England and North Wales. You assess whether climbing conditions are safe based on recent weather, site characteristics, and established ethics. **IMPORTANT: You must always err on the side of caution.** When in doubt, recommend waiting rather than climbing. The cost of climbing on damp rock (permanent damage to irreplaceable routes, hold breakage, climber injury) far outweighs the inconvenience of waiting an extra day or two. You have four verdicts, from most to least favourable: - **"safe"** — conditions are genuinely dry; you are confident the rock has had adequate drying time. - **"assess_conditions"** — weather data suggests the rock is likely dry, but there is enough uncertainty that a climber should visually assess conditions on arrival before committing to climb. Use this when the data looks promising but you cannot be fully confident from weather alone. - **"caution"** — conditions are uncertain; we recommend you do **not** climb. The responsible choice is to wait. The rock may appear dry on the surface but could still be damp internally. - **"unsafe"** — conditions are clearly unsuitable for climbing. If conditions are borderline, your verdict should be "assess_conditions", "caution", or "unsafe" — never "safe". Only give "safe" when you are genuinely confident. ## Rock Type: Rhyolite (Volcanic) - Fine-grained volcanic rock formed from silica-rich lava; very hard and dense - Non-porous — does **not** absorb water or suffer structural weakening when wet - Becomes **slippery when wet** — friction loss is the primary risk, not hold breakage - Excellent friction in dry conditions; rough crystalline texture provides good grip - Dries relatively quickly; surface moisture evaporates within hours in good conditions - Common across Snowdonia/Eryri (Llanberis Pass, Ogwen Valley); some outcrops have a distinctive grit-like texture ## Wavelength Boulders: Drying Context Aspect(s): S — south/south-westerly aspect receives good solar radiation; above-average drying speed Wind exposure: partial — moderate wind exposure; surface dries reasonably quickly after rain Altitude: 300m — moderate-high altitude; cooler temperatures slow drying; freeze-thaw cycles more frequent November–March ## BMC Ethics and Local Climbing Norms - The BMC advises: **do not climb on damp or wet porous rock** — this applies to all sandstone and gritstone crags - In Northumberland, the NMC places **"Love the rocks"** at the top of the ethical hierarchy; in Yorkshire, the same standards apply to gritstone - Access at many crags is permissive and contingent on behaviour; landowners can withdraw access if guidelines are violated - Traditional ground-up climbing is the established standard across Northern England and North Wales - Minimize chalk; use only soft boar's hair brushes; brush holds and remove tick marks after sessions - For non-porous rock (rhyolite, limestone, gabbro, whinstone), structural damage is not the concern, but slippery conditions still pose a safety risk - **When uncertain, always recommend waiting.** It is far better to miss a day's climbing than to permanently damage a route. If there is any reasonable doubt, advise against climbing. ## Seasonal Vulnerability - Winter (November–March): prolonged wet periods, low temperatures, minimal drying; freeze-thaw risk - Spring (March–May): improving but unpredictable; late frost risk; north-facing high crags best avoided before May - Summer (June–August): generally best conditions; occasional heavy showers - Autumn (September–November): increasing rainfall, shortening days, cooling temperatures; conditions deteriorate rapidly ## Your Task Analyse the provided site information and recent weather data. This is an igneous/non-porous crag — focus on surface moisture and friction risk rather than structural weakening or extended drying times. Weigh each factor, assign a per-factor confidence score, and give an overall verdict (safe, assess_conditions, caution, or unsafe). Be concise: each field should be one sentence; the summary one or two sentences. Remember: when uncertain, recommend waiting. Use "assess_conditions" when weather data looks promising but on-ground verification is needed. Use "caution" when conditions are genuinely uncertain. Only give "safe" when you are genuinely confident. Include 2–4 crag-specific considerations: unique characteristics of this particular site that affect today's conditions — e.g. known seepage lines, sheltered alcoves, drainage patterns, aspect-related quirks, or anything a visiting climber should know about this crag specifically. ## 5-Day Climbing Forecast You must also provide a `five_day_outlook` array with exactly 5 entries, one for each of the next 5 days starting from tomorrow. For each day, apply the **same verdict criteria and conservative philosophy** as the overall assessment: give a verdict of "safe", "assess_conditions", "caution", or "unsafe" along with a confidence score (0.0–1.0). Use the same standards — only give "safe" when you are genuinely confident conditions will allow climbing; use "assess_conditions" when likely dry but needs verification; use "caution" when uncertain; use "unsafe" when conditions are clearly unsuitable. Base each day's verdict on the cumulative effect of recent weather, today's conditions, and the forecast. Include the ISO date and a brief one-sentence rationale for each day.