WEATHERDUCK ALERT
Likely cloud inversion
Helvellyn area
Best window04:00–07:00
A Likely forecast area has reached your chosen alert range in two consecutive forecast updates.
Example email · values are illustrativeBuilt for walkers & dawn photographers
UK cloud inversion forecasts. Leave the fog in the valley.
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See mapped UK forecast areas, modelled cloud layer heights and the best viewing windows. Create a free account and we will also watch one mountain area for you.
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Very likely
Likely
Possible
Unlikely
Skiddaw, Lake District
Free cloud inversion alerts
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Choose a mountain area and WeatherDuck will email you when a Likely or Very likely inversion reaches it. We wait for two consecutive forecast updates before sending, which reduces jumpy one off warnings.
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WEATHERDUCK ALERT
Live UK pulse
Current conditions and the next 24 hours
Captured 24 Aug, 19:08 BST · outlook to Tue 20:00
Current UK state
No supported areas right now
Unlikely
Checked at 20:00
No nearby cluster reaches Possible or better. Isolated fog or a brief local signal can still occur.
Forecast areas · next 24 hoursSignal
-
No supported areas in the next 24 hoursUnlikely
These bands are model ratings, not calibrated probabilities. Inversion-layer and cloud-top heights are approximate, rounded model-level estimates above sea level. Open the forecast for a location to see its timing, atmospheric evidence and limitations.
More than fog on a map
What makes a cloud inversion likely?
WeatherDuck reads the atmosphere above each mountain region, then looks for calm, moist valleys beneath clearer summit air. Four signals work together to identify the most useful dawn window.
How the regional score works
A useful temperature inversion needs cold, moist air trapped low down, drier air above it and winds calm enough for the layer to hold together. WeatherDuck scores those signals across the surrounding mountain region and groups supported forecast points into the areas shown on the map and evaluated for alerts.
Forecast input: Met Office Seamless (UKV with Global fallback), delivered by Open-Meteo and captured throughout the day.
See our data sources and limitationsAtmospheric profile
Temperature and moisture changes reveal the lid and likely cloud depth.
Calm, moist valleys
Humidity, visibility and low level wind show whether cloud can stay pooled.
Terrain support
Mountain height and connected signals separate cloud seas from isolated noise.
Dawn timing
Night and sunrise hours reveal the most promising viewing window.
Forecast verification
Issued first. Checked against what happened.
Each report keeps the original forecast, observed outcome and limitations together. These cases show the evidence behind WeatherDuck without pretending every forecast is certain.
Tap o’ Noth, Aberdeenshire
A Very likely dawn signal was independently photographed.
Case detail
The report preserves the original forecast, independent photographs and a modelled capping inversion boundary near 323 m. It clearly separates that estimate from an observed cloud top measurement.
Beinn Liath Mhòr, Torridon
A Likely regional outlook was followed by independent dawn evidence.
Case detail
The result is recorded honestly as an area success while the nearest individual forecast point was weaker.
Cadair Idris, Eryri
A Very likely area persisted through eleven of twelve updates.
Case detail
The report also preserves the timing shift and explains why no numerical cloud height is claimed.
The evidence record will also include false alarms, misses and uncertain outcomes as it grows.
Browse forecast verificationBefore you set the alarm
Cloud inversion forecast questions
What is a cloud inversion?
Cold air can settle in valleys beneath warmer air. When enough moisture condenses in that trapped layer, low cloud or fog forms below the summits, creating a sea of cloud when viewed from above.
When are inversions easiest to see?
They are usually strongest around dawn after a calm, clear night. Autumn and winter often provide the best setups, although suitable conditions can occur at other times.
Does “Very likely” guarantee an inversion?
No. It is WeatherDuck’s strongest model signal, not a promise or a literal percentage probability. Local cloud, wind and visibility can still differ from the forecast.
Where does the forecast work?
You can search any UK location. The national pulse summarises a monitored mountain network, while the full forecast relates your searched place to its captured mountain region.
How often is it updated?
The inversion capture is scheduled throughout the day. The live pulse above shows when its current dataset was captured; forecasts can change as new model runs arrive.
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