Temperature is the least useful number on the page

It's the first thing most of us look at, and it's the figure that matters least. A July day at 14°C in the valley, with a 40 mph wind and rain sweeping the summits, will feel far colder than a still, bright February morning at 2°C. What you actually need to know is how the day will be shaped by wind, cloud and rain — and how those three interact with the terrain you've chosen.

Forecasts written specifically for hillwalkers and climbers give you exactly that, but they're dense. Learning to read one in five minutes rather than fifteen is a genuine skill, and it's one that will keep you comfortable and, occasionally, keep you out of trouble.

Wind: the number that decides whether you go

Wind is the single most common reason a walk turns miserable or dangerous. It dictates your pace, your body temperature, your balance on exposed ground, and whether a ridge is a pleasure or a fight. Look at both the average speed and the gusts — gusts are what knock you sideways.

• Up to 20 mph: noticeable on tops, rarely a problem. Sheltered corries and wooded glens will feel calm.
• 20–30 mph: hard work on ridges and plateaus, especially with a pack. Expect to lean into it.
• 30–40 mph: progress slows sharply, conversation stops, and balance on rocky ground becomes uncertain.
• Over 40 mph, gusting higher: for most hillwalkers this is a day for a low-level route or a valley walk. Exposed ridges and summits should come off the plan.

Check the direction too. A south-westerly is the classic UK hill wind, and it means the windward side of a mountain will be wetter, windier and claggier than the lee. Planning a route that climbs in shelter and returns down a sheltered glen is often smarter than fighting a headwind in both directions.

Cloud base: the difference between a view and a maze

Cloud base is the height at which cloud sits above sea level, and on UK hills it's the figure that catches people out most often. If the forecast says cloud base 600 metres and your summit is 900 metres, you'll spend the top third of the day in mist with visibility down to a few dozen metres. Navigation becomes a real task rather than a glance at the path.

Two things to weigh up:

• Is your route safe in poor visibility? Broad, well-trodden ridges are forgiving. Featureless plateaus, boulder fields and complex spurs are not.
• Can you navigate without following other people? If the answer is no, choose a lower route or wait for a day with a higher cloud base — and think about a navigation course before your next big outing.

Cloud base often lifts through the morning and drops again in the afternoon as showers build, so the timing of your summit matters as much as the number itself.

Precipitation: chance, timing, type and intensity

Rain is usually given as a percentage chance over a period. Read those percentages alongside the timing, never in isolation.

• A 30% chance all day is very different from a 30% chance concentrated into one hour.
• Intensity matters. Light drizzle is an inconvenience. Heavy rain on a long descent soaks clothing, chills the body and turns paths into greasy channels.
• In winter, check the freezing level and snow line. Rain in the valley can be snow above 700 metres, which changes both your equipment and your effort enormously.
• Think about the ground after the rain. Steep grass, eroded path junctions and river crossings can stay hazardous for hours after the showers have passed.

Build a picture of the day, hour by hour

Don't read a forecast as a single verdict — read it as a sequence. When does the wind pick up? When does the front arrive? Is cloud expected to lift by late morning, or drop by early afternoon?

Then map that sequence onto your route. If rain is due at two o'clock and you'd be on an exposed ridge at two o'clock, start earlier, reverse the route, or pick something shorter. Write a simple plan: where you expect to be at each hour, and what the weather is forecast to be doing there. Ten minutes of that changes the whole day.

Deciding to turn back

A forecast is a plan, not a promise. Conditions in the UK hills routinely turn out worse, or arrive sooner, than predicted. The skill is noticing early and acting without embarrassment.

Before you set off, agree a turnaround time with your group — a real one, written down. Then add these triggers:

• Wind stronger than forecast, or gusts that make you stagger.
• Cloud descending below the height you need to navigate safely.
• Rain arriving well ahead of schedule, or snow where rain was forecast.
• Anyone in the group getting cold, tired or unusually quiet.

Turning back isn't failure. It's the decision that means you get to walk again next weekend — and the hills will still be there waiting.