How to Survive a Heatwave

Most homes in northern Europe weren't built for this. No air conditioning, south-facing windows, stone or brick that absorbs heat all day and releases it at night. The body, meanwhile, is doing its best — sweating, diverting blood to the skin, trying to dump heat into an atmosphere that's already close to body temperature and not particularly interested in taking it.

When those systems start to fail, things can move quickly. Knowing the signs, and the practical steps to slow the spiral, matters more on a 38°C afternoon than any amount of general advice about "staying cool."

The difference between heat exhaustion and heat stroke

These are not the same thing. One is unpleasant and manageable. The other is a medical emergency.

Heat exhaustion happens when the body loses too much water and salt through sweat and can no longer regulate temperature properly. Symptoms: heavy sweating, pale and clammy skin, a fast but weak pulse, nausea, dizziness, muscle cramps, headache, fatigue. The person is still conscious, still coherent. Move them somewhere cooler, get fluids into them, lie them down with legs slightly raised. Most people recover within thirty minutes.

Heat stroke is what happens when the core body temperature climbs above 40°C and the cooling system breaks down. The sweating may actually stop. Skin becomes hot, red, and dry. The pulse is rapid and strong. Confusion, slurred speech, loss of consciousness. This is an emergency — call 999 (UK) or your local emergency number immediately. While waiting, move the person into shade or indoors, remove excess clothing, and cool them with whatever you have: wet cloths, a fan, cold water on the skin. Ice packs to the neck, armpits, and groin work fast.

The key difference: confusion and hot, dry skin point to heat stroke. Act fast.

Fluids and electrolytes

Drinking water is necessary but not sufficient when you're sweating heavily. Sweat contains sodium, potassium, and magnesium. Drinking large amounts of plain water in a short time without replacing those electrolytes can cause problems — headaches, nausea, muscle cramps — because it dilutes what's left.

For most people in normal heat, plain water is fine as long as you're also eating. A meal with some salt in it replaces most of what you lose. Electrolytes become genuinely important during sustained outdoor work or exercise in extreme heat, or when someone has already become ill and is replacing fluid lost through vomiting.

Practical options:

• Add a pinch of salt and a squeeze of lemon to water. It's not glamorous but it works.
• Coconut water contains potassium and is more palatable than sports drinks for many people.
• Sports drinks (Lucozade Sport, Powerade) replace electrolytes effectively — just not the sugary versions if you're drinking a lot.
• Oral rehydration salts (sold in pharmacies as Dioralyte) are the clinical standard for serious dehydration. Worth having in the house.

Signs you're well hydrated: pale yellow urine, urinating regularly. Dark yellow or infrequent — drink more. If someone isn't urinating at all for several hours, that's a warning sign.

Alcohol and caffeine are both diuretics. They don't cancel out your fluid intake but they add to the load. Keep drinking water alongside them.

Prevention: the basics

Much of this seems obvious but is frequently ignored until it's too late.

Timing. The temperature peaks between 11am and 3pm. If you need to do anything physical — gardening, cycling, carrying things — do it before 10am or after 6pm. During the peak, rest.

Clothing. Loose, light-coloured, natural fabrics (linen, cotton) let the skin breathe and don't trap heat. Tight synthetics are much worse. Wear a hat outdoors.

Wet skin works. Evaporation is how the body loses heat. A damp flannel on the back of the neck, wrists, or temples — anywhere blood vessels are close to the surface — cools you faster than any fan alone. A fan pointed at damp skin is the no-AC version of air conditioning.

Don't underestimate the car. A car parked in direct sun can reach 60°C inside within minutes. Never leave a child or animal in a parked car in a heatwave, even briefly.

Cooling your home without air conditioning

This is where most people struggle, because the temptation is to open windows and let air in. During a heatwave, this is backwards for most of the day.

Keep heat out during the day. Close windows and external shutters or blinds before the sun hits them. Close internal doors to keep cool air in the rooms you're using. Thick curtains — especially blackout lining — are surprisingly effective at keeping radiated heat out. The goal is to insulate your home against the outdoor temperature during peak hours.

Open up at night. Once outdoor temperature drops below indoor temperature — usually late evening — open everything: windows on opposite sides of the house to create a through-draught, loft hatches if you have them (hot air rises), bedroom windows before you sleep.

The overnight towel trick. Hang damp towels in front of open windows at night. The evaporation cools the incoming air. Works best in low humidity.

Ground floor stays cooler. Hot air rises. If you have the option, sleep downstairs on very hot nights. Basements and stone-floored rooms (kitchens, old utility rooms) are often ten degrees cooler than upstairs bedrooms.

Reduce internal heat sources. Ovens, tumble dryers, dishwashers, and even incandescent bulbs add significant heat to a room. During a heatwave, cook outside, eat cold food, or use a microwave. Hang laundry outside.

Electric fans don't cool the air — they cool your skin by increasing evaporation. In very high humidity they're less effective. Positioning matters: a fan drawing air from a cool room into a hot one is more useful than a fan just circulating hot air around one room.

Evaporative coolers (sometimes called swamp coolers) are cheap, use little electricity, and work well in dry heat. They pull air over water-saturated pads and reduce the temperature of the air they push out. In the dry, low-humidity heat that comes with European heatwaves, they can drop room temperature by 5–10°C. Worth buying if you don't have one.

Older people and those who are vulnerable

Heat illness is significantly more dangerous for older adults, young children, and anyone with a heart condition, kidney disease, diabetes, or who takes certain medications (diuretics, beta-blockers, antipsychotics, and others that affect temperature regulation or fluid balance).

Older adults are at greater risk for several reasons: the thirst sensation becomes less reliable with age, the body's ability to sweat efficiently reduces, and many live alone without someone checking in on them.

If you have an elderly parent, neighbour, or relative:

• Check in daily during a heatwave — a phone call if not a visit.
• Ask about medication. Some drugs make people much more susceptible to heat illness. Their GP or pharmacist can advise whether doses or timing should change.
• Don't assume they know they're overheating. Confusion is a symptom. An older person who seems muddled, unusually quiet, or says they feel fine when the room is clearly very hot may be in the early stages of heat stroke.
• Help them access a cool space. Shopping centres, libraries, and community halls are often air-conditioned. They exist and are free to sit in.

Babies and young children also can't regulate temperature well. Keep them out of direct sun, dress them lightly, and keep fluid intake up — breast milk or formula for infants, water for older children.

When to seek help

Heat exhaustion: if someone doesn't improve within 30 minutes of moving to a cool space and rehydrating, call NHS 111 (UK) or your local health line.

Heat stroke: call emergency services immediately. Don't wait.

Don't drive someone to hospital yourself if they're confused or unconscious. Emergency services can begin treatment on arrival.

If you're well enough to be outside: Running in summer heat · Gardening in a heatwave · Foraging in summer

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