Cold, wet and far from the car: hypothermia on lowland winter walks

Hypothermia is a dangerous drop in body temperature below 35C, and the NHS treats it as a medical emergency. On a lowland walk the usual route there is not extreme cold but a combination of wet clothing, wind, tiredness and a walk that takes longer than planned. If someone is shivering hard, slurring, confused or unusually slow, get them sheltered and out of wet clothes, and call 999.

The NHS page on hypothermia sets out the signs and first steps clearly, and it is worth reading once before winter rather than on a phone in the rain.

Why low ground catches people out

Normal body temperature is around 37C. Losing two degrees sounds a lot, and on a dry, still day in good clothing it would take a great deal of cold to get there. But water drains heat from the body far faster than air, and wind strips away the warm layer next to the skin. A walker in a wet cotton top on an exposed down or a flat river valley in a stiff wind can cool surprisingly quickly once they stop moving.

Short winter days make it worse. In London, daylight on 21 December lasts about 7 hours 49 minutes, according to timeanddate. A party that loses an hour to a muddy field or a wrong turn can find itself walking the last stretch in the dark, slower and colder than at the start.

The people most at risk on a family or group walk are often the ones least likely to say so: older walkers, small children carried in a sling or backpack who are not moving, and anyone who is tired, hungry or has had a drink at the pub halfway round.

Signs to watch for

The NHS lists these as the signs in adults:

• shivering
• pale, cold and dry skin, which may look blue or grey
• slurred speech
• slow breathing
• tiredness or confusion

In babies, it lists feeling cold to the touch, being floppy, being unusually sleepy, and refusing to feed. A baby in a carrier on a parent's back is not generating the warmth the parent is, and is worth checking often.

Confusion is the sign that matters most on a walk, because it stops the person concerned from noticing anything is wrong. Someone who is stumbling, lagging behind or giving odd answers deserves attention even if they insist they are fine.

What to do while you wait for help

The NHS advice for someone with suspected hypothermia, while waiting for help, is to:

1. Move them indoors or somewhere sheltered as quickly as possible. On a walk this might be a barn, a church porch, a bus shelter or the lee of a wall.
2. Remove any wet clothing and wrap them in blankets or dry towels, keeping the head covered. On the hill, spare dry layers and a survival bag do the job.
3. If they are fully awake, give them a warm non-alcoholic drink and a sugary snack.
4. Keep them talking and do not leave them alone.

Equally clear is the list of things not to do. Do not use a hot bath, hot water bottles or a heat lamp to warm them. Do not rub their arms, legs, hands or feet. Do not give them alcohol. The NHS says to call 999 or go to A&E if you think someone has hypothermia, and not to drive yourself.

This is general information, not medical training. A first aid course run by a recognised provider is a far better preparation than any article, and well worth a winter evening.

Layers that work in British winter weather

There is no need for specialist kit on most lowland routes, but the principle of layering matters. A thin base layer that does not hold water against the skin, a warm middle layer such as fleece or wool, and a windproof and waterproof shell on top. Add or remove layers before you get too hot or too cold, not after. Sweating into a fleece on a climb and then stopping in the wind at the top is a reliable way to get chilled.

Cotton is the classic mistake. Jeans and a cotton hoodie are comfortable in the car park and miserable once wet. The Countryside Code line about taking something warmer than you think you need is good advice that is easy to ignore.

Planning so it does not happen

• Choose a route that matches the slowest member of the group in winter conditions, and assume mud will add time.
• Know your escape points. On an Ordnance Survey map look for lanes, villages and pubs where you could cut the walk short.
• Check the forecast for rain and wind, not just temperature. Cold, still fog can also leave clothing damp; the Met Office explains that freezing fog forms in cold, clear, calm winter conditions.
• Eat and drink regularly. A body that has run out of fuel struggles to keep warm.
• Turn back early. Nobody has ever regretted cutting a cold walk short.

Winter walking is one of the great pleasures of the British year: empty paths, low sun, a pub fire at the end. The aim is simply to get everyone to that fire in good shape.