Heatwave Survival UK

Every winter, the UK spends months talking about staying warm. We insulate, draught-proof, and worry about the heating bill. Then summer arrives and we discover the problem we built: houses designed to hold heat in are very good at holding heat in. When a heatwave hits, the inside of a British home can become genuinely dangerous — and unlike the cold, the risk creeps up quietly.

This guide covers the human side of heatwave preparedness: how to recognise when heat is becoming a medical emergency, how to stay cool without air conditioning, and how to protect the people around you who are most at risk.

The UKHSA Heat Health Alert System

The UK Health Security Agency runs a four-level alert system from June to September. Knowing what each level means helps you decide when to act — and how urgently.

• Level 1 — Business as usual. Year-round baseline. No specific action needed beyond normal summer awareness.
• Level 2 — Alert. A heatwave is possible within the next few days. Check on vulnerable neighbours and relatives. Review any medications that need cool storage.
• Level 3 — Heatwave action. A heatwave is occurring or imminent. Social and healthcare services move to heightened response. Keep older people, young children and those with health conditions cool and well hydrated.
• Level 4 — National emergency. A prolonged severe heatwave with significant impact on health services. Follows government emergency protocols. In practice, this has only been triggered once in the UK — during the summer of 2022.

Alerts are issued by region, not nationally, so a Level 3 in the South East does not mean the same applies in Scotland. Check the UKHSA or Met Office websites for your area.

Heat Exhaustion vs Heatstroke — Know the Difference

These are not the same thing. One you can treat at home. The other is a 999 call.

Heat exhaustion happens when your body overheats but is still trying to cool itself. Signs include heavy sweating, pale and clammy skin, a fast but weak pulse, dizziness, nausea, headache and muscle cramps. The person is still conscious and alert.

Heatstroke happens when the body’s cooling system fails entirely. The key difference: sweating stops. Skin becomes hot, red and dry. The pulse is fast and strong. Confusion, slurred speech and loss of consciousness follow. This is a medical emergency.

If you are unsure which you are dealing with — call 999 and describe the symptoms. Do not wait to find out.

First Aid for Heat-Related Illness

Heat exhaustion — act quickly but stay calm:

• Move the person to a cool place immediately — indoors, in shade, or near air conditioning if available
• Lay them down and raise their feet slightly
• Give cool (not ice cold) water to drink — sip slowly. A rehydration sachet is better than water alone if available
• Cool their skin with a damp flannel or spray, and fan them
• Loosen tight clothing
• If there is no improvement within 30 minutes, or symptoms worsen — call 999

Heatstroke — call 999 immediately, then:

• Move them to a cool area and remove as much clothing as possible
• Cool them by whatever means available — ice packs to armpits and neck, cold wet towels, a fan, cool water poured over them
• Do not give fluids if they are confused or unconscious — there is a choking risk
• Put them in the recovery position if they lose consciousness
• Keep cooling until the ambulance arrives

Staying Cool Without Air Conditioning

Most UK homes have no air conditioning, and a standard electric fan does not cool the air — it just moves it. In a heatwave, that can feel like pointing a hair dryer at yourself. The approach that works in a British home is managing airflow and shading, not just throwing a fan at the problem.

• Close south and west-facing curtains before the sun reaches them — not after. Once the glass has been heating up for two hours, the damage is done.
• Open windows only when outside air is cooler than inside — typically after 9pm. Opening them during the hottest part of the day lets heat in.
• Create cross ventilation at night — open windows on opposite sides of the house to pull cooler air through.
• Sleep downstairs — heat rises. The bedroom is usually the hottest room in the house by evening.
• Use a damp cloth on your wrists, neck and forehead — these are pulse points where cooling the skin has the most effect.
• Avoid using the oven — it adds heat to the house. Cold meals, the microwave, or a slow cooker used outside are better options.
• Take a cool (not cold) shower before bed — cold showers cause the body to generate warmth in response. Cool is more effective.

Hydration — More Than Just Drinking Water

The guidance to “drink plenty of water” is correct but incomplete. In a sustained heatwave, especially if you are sweating heavily, water alone does not replace the electrolytes you are losing. A headache that persists after drinking water, or muscle cramps, can be a sign of electrolyte depletion rather than dehydration.

Oral rehydration sachets (the same ones used for illness) work well. A diluted sports drink is an acceptable alternative. Plain water is fine for normal hydration — it is only at the extreme end that the difference matters.

Signs of dehydration to watch for:

• Dark yellow or amber urine — aim for pale straw colour
• Headache and light-headedness
• Dry mouth, lips and eyes
• Fatigue and difficulty concentrating
• In serious cases: no urination for eight hours or more

Alcohol and caffeine both increase fluid loss. This is not a reason to avoid them, but it is a reason to compensate with extra water on top. Older people often lose the sensation of thirst — do not wait until you feel thirsty to drink.

Food Safety in the Heat

A domestic fridge should run at 5°C or below. In a heatwave, particularly if the kitchen faces south, it may struggle. A fridge thermometer costs very little and takes the guesswork out.

The practical rules:

• Do not leave cooked food at room temperature for more than two hours — in temperatures above 30°C, reduce that to one hour
• Bacteria that cause food poisoning multiply fastest between 8°C and 60°C — the fridge is your main line of defence
• If in doubt about something, throw it out — food poisoning in hot weather is significantly more dangerous than in winter, particularly for vulnerable people
• Defrost meat in the fridge rather than on the counter
• Buffet-style food left out at a summer gathering can become dangerous quickly

Medications That Need Keeping Cool

A number of commonly prescribed medications are temperature-sensitive and can lose effectiveness or become unsafe if stored in a warm environment. The most critical is insulin, which must be kept between 2°C and 8°C when not in use. Other medications to check include some eye drops, certain antibiotics (particularly liquid forms), some inhalers, and several types of antipsychotic and cardiac medication.

If you or someone in your household is on regular medication, check the storage guidance on the packaging or leaflet now — before a heatwave, not during one. Your GP or pharmacist can advise on travel or backup storage if your home is likely to get very warm.

Checking on Vulnerable People

Most heatwave deaths in the UK are among people over 75. The risk is also elevated for young children, people with heart, lung or kidney conditions, those on certain medications (diuretics, beta-blockers and antipsychotics all affect the body’s ability to regulate temperature), and anyone working or sleeping in a very hot environment.

The practical ask is straightforward: check in. A phone call or a knock on the door to an elderly neighbour during a Level 3 alert takes two minutes. Ask if they are drinking enough, whether they have been able to sleep, and whether they have somewhere cool to go if the house is unbearable. NHS 111 can advise if you are concerned about someone’s condition.

Signs that someone needs urgent help: confusion or unusual behaviour, difficulty breathing, not responding normally, or very hot and dry skin with no sweating. Call 999.

Your Pets in the Heat

Dogs, cats and other pets are just as vulnerable to heat-related illness as people — and they cannot tell you they are struggling. The most common and preventable risk for dogs is being walked on hot pavements: tarmac can reach temperatures of 60°C on a sunny day and will cause paw pad burns within minutes.

For a full guide to keeping pets safe in hot weather — and what to do if they show signs of heatstroke — see the dedicated guide below.

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Frequently Asked Questions