Reading the Hill Forecast Before You Lace Your Boots
A general weather forecast can mislead on higher ground. Learn what wind, cloud base and freezing level mean for a hill walker and how to plan around them.
A pleasant forecast for the nearest town does not always translate into a pleasant day on the hill. Higher ground is colder, windier and wetter than the valley, and clouds that sit politely overhead in the lowlands can wrap right around a summit. Learning to read a forecast with hills in mind is one of the best habits a walker can develop.
Why the hills are different
As a rule of thumb, air cools as you climb, by roughly 6 degrees Celsius for every thousand metres of height gained, though the exact figure varies from day to day. A 12-degree afternoon in the valley can be close to freezing on a summit of a thousand metres, before you count the wind. Wind is usually stronger on exposed tops too, as the air is forced up and over ridges.
Choosing a forecast
A general town forecast has its uses, but for hill walking it helps to look for sources that give mountain or upland detail. The Met Office publishes forecasts for national parks and mountain areas, and some regions have dedicated mountain weather services. Compare two sources if you can. If they disagree, plan for the worse one.
The numbers that matter
When you look at an upland forecast, focus on a handful of details:
- Wind speed and gusts. Wind makes it feel much colder, and strong gusts can make ridges and summits uncomfortable or unsafe. Gusts matter more than the average.
- Cloud base. This tells you how high the cloud sits. If the base is below the summit, you will be walking in mist, which makes navigation harder. A low cloud base is a good reason to choose a route with clear paths or a lower alternative.
- Visibility. Poor visibility can disorient even experienced walkers.
- Freezing level. The height above which temperatures are below freezing. If the freezing level is below your route, expect ice and snow on the ground.
- Rain timing and intensity. Rain at midday is different from rain at dawn. Heavy rain also swells streams, which can make crossings tricky.
- Temperature and wind chill. The feels-like temperature is the one your body will respond to.
Matching the plan to the forecast
A calm approach is to decide in advance what conditions would change your plan. For example, you might decide that gusts above a certain strength mean taking a sheltered valley route instead of a ridge. Or that if the cloud base is below the summit, you will choose a woodland or river walk. Our calm beginner's checklist for planning a day walk in the hills suggests building in an alternative before you set out.
Changes during the day
Forecasts are not guarantees. Watch the sky as you walk. Signs that conditions are worsening include thickening cloud, a drop in temperature, a change in wind direction and a sudden clearing of distant views, which can sometimes come before rain. If you notice any of these, it is sensible to shorten your route and turn back early.
What to carry for the conditions
If the forecast is uncertain, carry extra layers, a hat and gloves, and a good waterproof, even if it looks sunny at the car park. Food and a hot drink help you stay warm. On the coast, add tide times to the list, as described in our guide to walking the coast path safely.
Checking at the last minute
Look at the forecast the day before and again on the morning of the walk. If you are going into more remote country, check conditions at the visitor centre or with a local outdoor shop, since local staff often have a feel for how the weather behaves in the area.
Frequently asked questions
Is a town forecast good enough for a hill walk? It is a start, but it often understates wind and cold on higher ground. Use an upland or mountain forecast where you can.
What wind speed is too strong to walk in? There is no single number, as it depends on your experience, the route and the exposure. On high, exposed ground, strong gusts can knock you off balance, so be cautious and choose a lower route when in doubt.
What should I do if the cloud comes down? Stop, check your map and compass, and follow a known route back. Do not guess your way down. If you are unsure, retrace your steps to the last place you were certain of.