Reading the Fell Forecast: MWIS, Met Office, and What to Actually Trust

The number of people who check the Met Office forecast for Keswick before heading up Helvellyn, see 'partly cloudy, 12 degrees', and set off without a waterproof is not small. Valley weather and fell weather are not the same thing. At 900 metres the temperature is roughly 5 degrees colder, the wind can be three times stronger, and cloud that sits above the valley floor puts you in zero visibility.

There are forecasts written specifically for fell conditions. Use those.

MWIS: Mountain Weather Information Service

MWIS (mwis.org.uk) produces daily forecasts for mountain areas across the UK including the Lake District. The forecast is written in plain English and addresses the specific conditions you will encounter at altitude: cloud base, wind speed and direction at summit height, freezing level, visibility.

Read the cloud base figure carefully. If the cloud base is at 600 metres and your target fell is 800 metres, you will be walking in cloud for the upper third of the route. That is not necessarily a reason not to go, but it changes what the day will be.

The wind figure at summit height is the one that catches people out most often. A 30 mph wind at valley level is an annoying breeze. A 30 mph wind at 900 metres with gusts to 50 mph is serious. MWIS publishes both a summit wind speed and a note on whether it is safe to be on exposed ridges. Read it.

Met Office Mountain Forecasts

The Met Office produces mountain-specific forecasts for the Lake District that are more detailed than the general area forecast. Go to metoffice.gov.uk and find the Mountain Forecasts section. These are updated twice daily and include summit temperature, wind, and weather. Slightly more conservative in their wording than MWIS.

The general Met Office area forecast for Cumbria is fine for planning a trip. It is not sufficient for deciding whether to attempt a fell.

The Freezing Level

The freezing level appears in mountain forecasts and is important in autumn, winter, and spring. If the freezing level is at 500 metres and you are going to 900 metres, the upper 400 metres of your route will be at or below zero. Wet rock at below zero is ice. Paths become hard to follow. The consequences of a slip are different.

This is where walking equipment transitions to mountaineering equipment. If the freezing level is at or below your target summit for a significant part of the day, you need crampons and an ice axe and the skills to use them. If you do not have those, pick a lower-level route or go on a different day.

What Actually Causes Problems

• →Zero visibility in cloud when you do not have a compass or cannot use one
• →Wind at summit height that has been underestimated from valley conditions
• →Wet rock on steep descents, particularly on limestone and slate
• →Temperature drop after dark on late autumn days when days are short
• →Rain that seems light but soaks you over three hours because you did not bring waterproof trousers

When to Abort

The decision to turn back before reaching a summit is one that experienced walkers make frequently without drama. If visibility drops and you are not confident navigating on a compass, go down. If the wind has strengthened beyond what you expected and the ridge feels unstable, go down. The fell will be there next time.

No summit is worth a rescue. The Mountain Rescue teams in the Lakes are excellent, but they are volunteers, and a call-out because someone pressed on in conditions they were not equipped for is avoidable.