Checking the weather before a hill walk is not optional. UK upland conditions change faster and more dramatically than valley weather, and the gap between a pleasant day and a dangerous one can be a matter of hours. Getting this right is one of the most practical skills you can develop as a UK hillwalker.

Why Valley Forecasts Do Not Work

The weather app on your phone shows conditions at a location near sea level. In the UK, conditions at 700 metres and above can be materially different:

  • Temperature: The lapse rate in the atmosphere means temperature drops approximately 0.65°C for every 100 metres of altitude. A 12°C morning in the valley can mean 7°C or lower on a 700m summit, and considerably colder with wind chill.
  • Wind: Wind speed increases with altitude. A light breeze in the valley is often a strong wind on an exposed ridge.
  • Visibility: Cloud that appears as high overcast from below may be sitting at summit level, reducing visibility to metres.
  • Precipitation: Rain in the valley can be sleet or snow on the tops, particularly in spring and autumn.

Using a valley forecast for upland walking leaves you with an incomplete picture.

Where to Get a Mountain Forecast

MWIS (Mountain Weather Information Service) — the most widely used specialist mountain forecast service in the UK. Covers all major UK upland areas including the Lake District, Snowdonia, the Cairngorms, Brecon Beacons, and more. Forecasts are written in plain language and updated twice daily. Free to access at mwis.org.uk.

Mountain Weather — Met Office — the Met Office produces mountain forecasts for specific areas including the Lake District and Scottish Highlands. Clear, reliable, and trustworthy. Available via the Met Office website.

SAIS (Scottish Avalanche Information Service) — relevant for winter walking in Scotland specifically. Issues avalanche hazard ratings and forecasts for snow conditions. Essential reading for anyone planning winter hillwalking in the Cairngorms, Glencoe, Lochaber, or the Northern Cairngorms.

Weather Horizon — a well-regarded source for UK hill forecast modelling used by many mountain leaders and guides.

What to Look for in a Forecast

When reading a mountain forecast, the key information to extract:

Summit temperature: At what temperature will you be operating at the highest point? Factor in wind chill on top of this. A summit temperature of 5°C with 40mph winds feels like approximately -5°C.

Wind speed and direction: Strong winds on exposed ridges affect safety, navigation, and how quickly you cool down when you stop. Check direction to understand which sides of hills will be sheltered and which will be exposed.

Cloud base: Compare this to your intended highest point. If cloud base is below your summit, plan for reduced visibility on the upper section.

Precipitation and type: Rain is manageable with good waterproofs. Sleet or snow changes the equation in terms of footing, navigation, and how quickly you become cold if you stop.

Freezing level: Relevant in autumn, winter, and early spring. If the freezing level is below your summit, ice is possible on paths and surfaces. This is when traction devices become relevant.

Visibility: Forecasts often rate visibility as excellent, good, moderate, or poor. Poor visibility on unfamiliar terrain with a non-obvious path requires solid navigation skills and a map and compass, not just a phone.

Making the Decision

A mountain forecast gives you information. The decision on whether to proceed, adjust, or cancel is still yours.

Some useful rules of thumb:

  • If the forecast is borderline, plan for the worse end of the range, not the better.
  • Have a lower-level alternative planned that you are willing to take if conditions on approach suggest the forecast was optimistic.
  • Check the forecast again the morning of your walk, not just the night before. Forecasts improve in accuracy within 24 hours.
  • If you are leading others, factor in the group’s experience and fitness alongside the weather. Conditions that are manageable for an experienced hillwalker may not be appropriate for a mixed group.

Turning back is not failure. Mountain rescue statistics consistently show that the majority of incidents involve people continuing into deteriorating conditions. Getting into the habit of reading and acting on forecasts properly is one of the most valuable things you can do as a hillwalker in the UK.