The forecast said 6°C and a light breeze, and in the car park it was exactly that. Three hours later, on a ridge 700m higher, it is close to freezing, the wind is strong enough to lean into, and the cotton t-shirt soaked on the climb is pressed cold against your back. The forecast was right. It was the forecast for the car park.
Many uncomfortable winter walks come from dressing for a forecast written for somewhere else: the town rather than the summit, the harbour rather than the headland.
A valley forecast is not a summit forecast
Air cools with height: very roughly 0.6 to 1°C for every 100m you climb, the lower figure typical in cloud and rain, the higher in dry air. That is 2 to 3°C for every 300m of ascent. Fort William sits at sea level and the summit of Ben Nevis is 1,345m above it, so the top is something like 8 to 13°C colder before the wind is counted.
The wind is stronger too. Hedges, trees and rough ground slow the air near the surface; summits stand clear of them, and ridges and gaps between summits squeeze the flow and speed it up. Summit winds are often double the valley speed or more. A 35mph wind across a top at around freezing gives a feels-like temperature near minus 8°C: a different day from the 6°C you dressed for.
On still, clear days the reverse can happen: cold air pools in the valleys and the tops are milder and sunnier. Treat that as a bonus, not a plan.
Take the valley temperature, knock off 2 to 3°C for every 300m of climbing, then check the summit feels-like figure on a mountain forecast. Dress and pack for that number, not the one in the car park.
Where to find the forecast for the tops
Two free services forecast for the hills. Read both the evening before and again in the morning, and if they disagree, plan for the worse.
- Met Office mountain forecasts cover ten areas, including the Lake District, the Peak District, Eryri (Snowdonia), Bannau Brycheiniog (the Brecon Beacons) and four in the Scottish Highlands. They give wind, gusts, temperature and feels-like at 900m, 600m, 300m and in the valley, plus the freezing level and the chance of cloud-free tops.
- The Mountain Weather Information Service (MWIS) also covers ten areas, including the Southern Uplands, and is written in plain language. Its "Effect of the wind on you?" line is often the most useful on the page.
If the freezing level is below your summit, expect frozen ground, ice on rock and possibly snow. Walking in cloud also wets your outer layer even when nothing is falling. In the Scottish Highlands in winter, check the Scottish Avalanche Information Service too.
For a lowland walk the ordinary forecast is enough, provided you read the feels-like and gust figures rather than the headline number (wind chill and feels-like temperature explains why) and check for weather warnings.
Three layers, adjusted all day
The three-layer system is set out in the UK layering guide. Walking adds one complication: you make a lot of heat climbing and very little standing still.
- Base layer: merino or synthetic, to move sweat off your skin. Not cotton.
- Mid layer: a fleece or light synthetic insulated top, the layer that comes off most often.
- Shell: a waterproof jacket with a close-adjusting hood, ideally with pit zips. See waterproof jackets and coats for features and waterproof ratings explained for the numbers.
The skill is managing sweat. Set off slightly cool, because warm in the car park means damp ten minutes into the climb. Vent before you overheat: front zip, then pit zips, then hat and gloves off. Take the mid layer off at the bottom of a long climb, not halfway up, and put a layer on the moment you stop, before you feel cold. Staying warm is far easier than getting warm again.
Carry one more insulating layer than you expect to need, usually a synthetic insulated jacket, which keeps more warmth when damp than down does.
Why cotton is a poor choice when wet
Cotton soaks up water and gives it up slowly. Once it is wet with rain or sweat, water fills the air spaces that were keeping you warm, and on an exposed top the wind evaporates that moisture from you, taking heat with it. A t-shirt merely damp on the climb becomes a cold compress at the summit.
Synthetics hold little water and dry quickly; wool holds much of its moisture inside the fibre and still feels warm when damp. The FAQ covers fabrics more generally.
Legs: walking trousers rather than jeans
Jeans are the commonest cotton mistake: wet denim is heavy, clings, chafes and takes hours to dry. Walking trousers are light, quick-drying synthetic, often with stretch for stiles, and thermal leggings underneath add a lot of warmth on a cold day.
Carry waterproof trousers on every winter walk. They block wind on a summit as well as rain, and long side zips let you pull them on over boots without sitting in the mud.
Feet: boots, shoes, socks and mud
In winter the ground decides the footwear more than the distance does: mud on lowland field edges and bridleways, bog and wet rock higher up.
- Walking boots with a waterproof lining, a deep-lugged sole and some ankle height suit wet hill ground and deep mud; the higher cuff keeps out shallow water.
- Trail shoes are lighter and fine on firm, well-drained paths. On a wet day, expect wet feet: tolerable while moving, cold when you stop.
- Gaiters keep water and mud out of the boot on peat moorland in the Pennines or on Dartmoor, or any path that is more puddle than path.
A waterproof lining keeps water out until it comes over the top, then keeps it in. Wool or wool-rich socks stay warm when damp, cotton socks do not, and a spare pair weighs almost nothing. Break new boots in on short walks first.
On low ground, ice is the underestimated hazard: shaded paths, stone flags and footbridges stay frozen long after the sun has reached everything else. Slip-on spikes help there, but they are not crampons, and snowy or icy hills need proper winter kit and skills, or a lower route.
Hands and head
Gloves get wet from rain, sweat and every gate you open. Wear a thin pair for the climb, keep warmer waterproof gloves or mitts for the top, and carry a spare pair. Mitts are warmer because your fingers share their heat.
Losing most of your heat through your head is a myth, but the head is usually the part left uncovered, so a hat is the cheapest warmth you can add. A peaked cap under the hood keeps rain off your face, and a buff or neck tube seals the collar where wind gets in.
Short days: plan around the light
On the shortest day London gets about 7 hours 50 minutes of daylight and Edinburgh just under 7 hours, and both see sunset before 4pm for almost all of December. In a deep valley the sun goes earlier still, and the temperature drops with it.
Naismith's rule, devised in 1892 and still the standard planning rule for British hill walkers, allows an hour for every 5km plus ten minutes for every 100m of ascent. A 14km walk with 700m of climbing is about four hours moving, nearer five with stops and mud. Start at 11am and you finish after sunset; start at 9am and you have nearly two hours in hand.
Carry a headtorch on every winter walk, even if you plan to finish in daylight; a phone torch drains the battery you may need for a call. Keep the warm layer handy too, because the temperature falls fast once the sun goes.
Coastal walks: wind, spray and cliff edges
The coast is usually milder than inland in winter, with less frost, but windier. An onshore wind crosses open water with nothing to slow it, headlands speed it up, and the harbour forecast can fall well short of what you meet on the cliff top.
Coast paths are rarely flat: stretches of the South West Coast Path and the Pembrokeshire coast drop into every cove and climb out again, so you heat up and cool down repeatedly, and pit zips earn their place.
Salt spray wets clothing as thoroughly as rain, and the salt left behind draws moisture from the air, so rinse spray-soaked kit in fresh water or it will stay clammy. A close-cinching hood and a brimless hat cope best with the wind.
Stay well back from cliff edges in strong or gusty wind: gusts are erratic where air is forced up a cliff face, and edges can be undercut, especially after heavy rain. If the route uses a beach or causeway, check the tide times.
Matching layers to the conditions
| Conditions | Wear | In the pack |
|---|---|---|
| Lowland, dry, 5°C to 10°C | Base layer, light fleece, walking trousers, boots or trail shoes | Waterproof jacket, hat, gloves |
| Lowland, steady rain, 4°C to 8°C | Base layer, light mid layer, waterproof jacket and trousers, boots, gaiters | Spare socks and gloves, dry warm layer |
| Frost and sunshine, around 0°C | Base layer, warm mid layer, shell, hat, gloves | Insulated jacket, flask, slip-on spikes for icy paths |
| Hills, summit near 0°C, wind 25 to 40mph | Base layer, mid layer, waterproof shell, hat, thin gloves, buff | Insulated jacket, waterproof trousers, warm gloves or mitts, spare gloves, map and compass |
| Coast path, onshore wind 25 to 40mph, showers | Base layer, mid layer, waterproof shell with a close-fitting hood, brimless hat | Waterproof trousers, warm layer, spare gloves |
| Snow or ice on the tops | Winter mountaineering kit: stiff boots, crampons, an ice axe and the skills to use them | Without those, a lower route below the freezing level |
What to carry, and a checklist
A winter day pack holds the warm layer and waterproof trousers you are not wearing yet, plus a flask and a map. A hot drink at the top does more for morale than its calories suggest. A paper map and compass do not run out of battery, provided you can use them; a phone does, faster in the cold, so keep it in an inside pocket. Most rucksacks are not waterproof, so use a liner bag.
Wear
- Merino or synthetic base layer
- Fleece or light insulated mid layer
- Waterproof jacket with an adjustable hood
- Walking trousers, thermal leggings if cold
- Wool socks, boots or trail shoes, gaiters
- Hat, thin gloves, buff
Carry
- Insulated jacket or spare warm layer
- Waterproof trousers
- Warm gloves or mitts, spare gloves and socks
- Map, compass, charged phone, power bank
- Headtorch and spare batteries
- Flask, food and water
- First aid kit, whistle, survival bag
- Rucksack liner
Before you set off
Tell someone your route and when you expect to be back, and set a turnaround time. If the wind is stronger than forecast, the cloud comes down or you fall well behind, turn back: coming down early is a normal part of winter walking, not a failure. In an emergency, call 999 or 112 and ask for the Police, then Mountain Rescue; on the coast, ask for the Coastguard.
The outfit tool gives a starting point from your postcode's forecast; on a hill day, treat it as the valley half of the picture and add the summit forecast. The guide to dressing for UK weather covers the principles behind both.