Raised sea-state signal
Waves and spray may affect lower rock and ledges. Higher modelled water around 09:00 coincides with a raised sea-state signal. Check official tide times.
Thursday 8 October · 08:00 to 18:39 local time
From 08:00 or sunrise, whichever is later, until sunset. Tide-related turns below cover the full calendar day.
Offshore waves
0.8 to 1.3 mSignificant wave height, not the largest individual wave.
Swell
0.3 to 0.7 mPeriod 3.9 to 5.2 seconds. Longer-period swell can matter even in light wind.
Coastal wind
11.2 to 18.1 mphGusts 19.2 to 29.1 mph. Model 10 m open-ground wind, not face or belay wind.
Rain and temperature
3.7 mm11.6 to 13.1°C. Rain covers source hours overlapping the daytime window.
Coast and spray
Spray possible
- A notable offshore sea state is forecast.
- Waves approach the broad coast-facing direction.
- Onshore wind may carry spray inland.
Broad westerly coast exposure for testing, inferred from location and regional guide context. Individual walls and wave shelter are not resolved.
Spray is an uncalibrated indication, not a probability or a height prediction. A lee wind does not establish shelter from swell.
Predicted astronomical tides
Calculated every five minutes from harmonic constants fitted to the nearby tide gauge's measured record. Some locations can have genuine secondary highs and lows.
- Low tide03:15
- High tide09:38
- Low tide15:32
- High tide21:45
Holyhead tide gauge, about 4 km from the crag. Local timing and wave reach at the cliff can differ. Times are predictions, not observations at the crag. Heights are deliberately omitted because they are not tied to a climbing ledge or chart datum here.
Total water-level model
Approximate peaks and dips in total sea level, including tide and weather effects. Source resolution is hourly, not a guarantee of timing accuracy.
- Model level dipAbout 03:00
- Model level peakAbout 09:00
- Model level dipAbout 15:00
- Model level peakAbout 21:00
The total-water heights use mean sea level, not chart datum. Do not compare them directly with guidebook tidal-access heights.
Different parts of the crag
Lower cliff and starts
Route starts, traverses and escape options require a route-specific guide and an on-site sea check.
Upper face and top-out
Marine conditions below still matter for approach and retreat. Upper rock is not guaranteed to be beyond spray.
How conditions change through the day
Directions show where wind and waves approach from, relative to the provisional broad coast aspect, not a surveyed climbing face.
| Time | Model water | Waves | Swell | Wind |
|---|---|---|---|---|
| 08:00 | 0.9 m MSL Rising | 1.3 m Towards coast | 0.4 m, 5.3 s Along coast | 14.1 mph Towards coast |
| 09:00 | 1.1 m MSL Changing slowly | 1.2 m Towards coast | 0.6 m, 4.9 s Along coast | 13 mph Towards coast |
| 10:00 | 0.8 m MSL Falling | 1.1 m Towards coast | 0.7 m, 4.6 s Along coast | 11.9 mph Towards coast |
| 11:00 | 0.2 m MSL Falling | 1.1 m Towards coast | 0.7 m, 4.4 s Along coast | 11.9 mph Towards coast |
| 12:00 | -0.6 m MSL Falling | 1 m Towards coast | 0.7 m, 4.2 s Along coast | 11.4 mph Towards coast |
| 13:00 | -1.5 m MSL Falling | 0.9 m Towards coast | 0.7 m, 4 s Along coast | 11.4 mph Towards coast |
| 14:00 | -2.1 m MSL Falling | 0.9 m Towards coast | 0.6 m, 3.9 s Along coast | 11.2 mph Towards coast |
| 15:00 | -2.2 m MSL Rising | 0.8 m Towards coast | 0.5 m, 3.9 s Along coast | 12.3 mph Towards coast |
| 16:00 | -1.8 m MSL Rising | 0.8 m Towards coast | 0.5 m, 3.9 s Along coast | 13 mph Towards coast |
| 17:00 | -1 m MSL Rising | 0.9 m Towards coast | 0.4 m, 3.9 s Along coast | 14.1 mph Towards coast |
| 18:00 | -0.1 m MSL Rising | 1 m Towards coast | 0.3 m, 3.9 s Along coast | 18.1 mph Along coast |
How this preview works and what is missing
Astronomical tides use 50 harmonic constituents from TICON-4, fitted to many years of measured tide-gauge data. The Moon and Sun are represented through these astronomical constituents, while local coastal shape is learned from the gauge record. Wind and pressure are not added to that curve.
Separately, we combine Open-Meteo waves, swell and total sea-level forecasts with local weather and a provisional coast-facing direction. Larger waves, longer periods and waves approaching the coast strengthen the sea-state signal. Onshore wind strengthens the spray signal. These are transparent research rules, not calibrated predictions of wave reach.
We do not add swell to total wave height because total waves already include swell. We also keep the astronomical tide and weather-affected total-water model separate to avoid counting surge twice.
- Offshore model guidance, not conditions at a particular ledge. Individual waves can exceed the quoted significant height. Check official tide tables, route access and the sea on arrival; no safe-access window is calculated.
- Spray signals are provisional rules, not calibrated probabilities or spray-height predictions.
- The pilot does not resolve bathymetry, wave refraction, reflected waves, surge residuals separately or salt deposits on holds.
- A sheltered wind direction does not establish shelter from swell. Offshore direction never establishes safe access.
No climbing score, safe-access interval or notification is produced. These crags are excluded from live rankings. Rock type is descriptive here; salt, seepage and drying are not yet modelled for this pilot.
Returned marine grid centre: 53.3, -4.7. Small coves, headlands and ledges are not resolved.