Why hypothermia catches hill walkers out

Hypothermia is not just a winter problem. On British hills, a wet and windy summer day can drop your core temperature faster than a dry, still, frosty morning. Wind chill strips heat from exposed skin, rain soaks through clothing, and once you stop moving, your body has very little defence. The danger is that the early stages feel subtle. You might just feel a bit quiet, a bit clumsy, a bit tired. That is exactly when you need to act.

The early warning signs to watch for

Mild hypothermia begins when your core temperature falls below about 35°C. The signs are often easier to spot in someone else than in yourself. Look for the "umbles": mumbles, stumbles, fumbles and grumbles. The person may become unusually quiet, irritable or withdrawn. They may insist they are fine when they clearly are not. Watch for:

• Uncontrollable shivering — not just a shiver you can stop by moving, but persistent, violent shaking.
• Slurred speech — words become thick, slow or muddled.
• Clumsiness — fumbling with zips, dropping gloves, tripping on easy ground.
• Confusion or apathy — losing interest in the route, not answering questions, or making poor decisions.
• Cold, pale skin — especially on the trunk, with blue lips or fingertips.
• Slow, shallow breathing — this is more serious and needs urgent help.

If shivering stops but the person is still cold, confused or drowsy, that is a red flag. It can mean moderate or severe hypothermia. Do not delay.

What to do the moment you spot trouble

Act immediately. Do not wait for the person to "warm up on the walk down". Shelter is your first priority. Get out of the wind and rain behind a wall, in a hollow, or inside an emergency shelter or bothy bag. Insulate the person from the ground using mats, rucksacks or spare clothing. Get them out of wet clothes and into dry layers. Add hats, gloves, fleece and an insulated jacket. Wrap them in a sleeping bag or foil blanket if you have one.

Warm the core first — chest, back, neck and head. Use your own body heat if necessary. If the person is fully conscious and can swallow, give warm, sugary drinks. No alcohol. Do not rub their limbs, do not put them in a hot bath, and do not apply direct intense heat. Rapid rewarming can cause dangerous afterdrop, where cold blood from the limbs returns to the core and drops the temperature further.

If symptoms are more than mild, or if you are unsure, call for help. Dial 999, ask for the police, then mountain rescue. Give your location, a grid reference if possible, the person's condition and how many are in your group. Keep the person horizontal and still. If they become unconscious but are breathing, place them in the recovery position. If they stop breathing, start CPR.

Warming someone slowly and safely

Slow and steady is the rule. Once sheltered and insulated, keep checking breathing and consciousness. Share a sleeping bag or use extra layers to create a warm microclimate. Warm the trunk before the extremities. If you have heat packs, wrap them in cloth and place them in the armpits, groin or neck — never directly on bare skin. Continue to monitor. If the person is shivering again, that is a good sign, but it does not mean they are out of danger. Keep them warm and get professional help if symptoms were moderate or severe.

How to avoid hypothermia on British hills

Prevention is always better than cure. Check the mountain weather forecast for wind speed, precipitation and wind chill, not just temperature. Dress in layers: a wicking base layer, a fleece or synthetic mid layer, and a waterproof shell. Avoid cotton next to the skin. Carry spare dry layers, a hat, gloves and an emergency shelter in a dry bag. Eat and drink regularly — even small sips and snacks help your body produce heat.

Pace yourself to avoid sweating, because wet clothing chills you quickly when you stop. Keep an eye on your group. Ask direct questions: "Are you warm? Are you shivering? How are your hands?" If someone is quiet, slow or clumsy, stop and address it. Turn back if the weather or the group's condition deteriorates. The hills will still be there another day.