How to prepare for a heatwave and stay safe in extreme heat
Before a heatwave, store extra water (4–5 litres, 1.1–1.3 US gal, per person per day), plan how to keep one room cool and check on older neighbours. During it, keep curtains and windows closed while it’s hotter outside, ventilate at night, avoid the sun in the hottest hours and drink regularly. A body temperature above 39.4 °C (103 °F) with confusion or hot, dry skin can be heatstroke: call the emergency number.
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Why heat is a real emergency
The World Health Organization describes extreme heat as one of the deadliest natural hazards, and Ready.gov says it causes more deaths each year than any other weather hazard in the US. Heat is dangerous because it builds up over several days, especially at night, and because it affects people quietly at home. Heatwaves can also cause power cuts when demand for cooling peaks, so a heat plan and a blackout plan go together.
Who is most at risk
- People over 65, especially those living alone.
- Babies and young children.
- People with heart, lung or kidney disease, diabetes, or mental health conditions, and people taking medicines that affect sweating or fluid balance (ask your doctor or pharmacist).
- Pregnant women, outdoor workers and people who exercise in the heat.
- People living in top-floor flats or poorly insulated homes.
If you have older relatives or neighbours, agree to call or visit them daily during a heatwave.
Before the heatwave
- Store extra water: at least 4–5 litres (1.1–1.3 US gal) per person per day for drinking in hot weather. See how much water to store.
- Choose your coolest room, usually north-facing or on a lower floor, as the place to sleep and rest.
- Fit or check blinds, shutters and blackout curtains; reflective film on sun-facing windows helps.
- Charge a power bank and a rechargeable fan in case of a blackout.
- Check how to store medicines: many must be kept below 25 °C (77 °F). See emergency preparedness with medication needs.
- Find cooling centres: libraries, shopping centres and municipal “climate shelters” in many European cities.
- Follow heat warnings from your weather service (AEMET, Météo-France, the Met Office and others).
During the heatwave
- Keep the heat out: close curtains and windows on sunny sides during the day, as the NHS advises; open them at night when it is cooler outside.
- Stay out of the sun in the hottest hours, roughly 11:00 to 15:00 (later in Spain and southern Europe).
- Drink regularly, before you feel thirsty. Water is best; avoid alcohol.
- Cool your body: cool showers, a damp cloth or cooling towel on the neck, wrists and feet in cool water.
- Eat light: salads, fruit, cold meals. Cooking heats the home.
- Never leave anyone, or a pet, in a parked car.
- Use an indoor thermometer to know when the room is cooler than outside.
Heat exhaustion vs heatstroke
| Heat exhaustion | Heatstroke | |
|---|---|---|
| Signs | Heavy sweating, paleness, cramps, tiredness, weakness, dizziness, headache, nausea | Body temperature above 39.4 °C (103 °F); red, hot, dry skin; fast pulse; confusion; fainting |
| What to do | Move somewhere cool, lie down, loosen clothes, sip water or rehydration drinks | Call the emergency number (112 / 911) immediately |
| While waiting | Get medical advice if it doesn’t improve within an hour | Move to shade, remove outer clothes, cool with wet cloths or ice packs on neck, armpits and groin |
Keep oral rehydration salts in the kit for heat and stomach upsets.
If the power goes out in a heatwave
- Keep the fridge and freezer closed; food stays cold about four hours in a closed fridge.
- Use a battery fan with damp cloths, and move to the coolest room or a cooling centre.
- Check on vulnerable neighbours; lifts and water pumps may stop in tall buildings.
- Never run a generator indoors. See what to do in a power blackout.
Heatwave kit
| Product | Best for | Key spec | Buy |
|---|---|---|---|
| Rechargeable fan | Blackout in the heat | USB, runs from a power bank | Check price on Amazon |
| Cooling towels | Quick cooling | Reusable | Check price on Amazon |
| Oral rehydration salts | Dehydration | Sachets | Check price on Amazon |
| Blackout curtains | Keeping the sun out | Thermal lining | Check price on Amazon |
| Indoor thermometer | Knowing when to ventilate | Digital | Check price on Amazon |
We don’t list prices because they change often. Use the button to see the current price on Amazon.
Full list: our heatwave kit.
Questions people ask
How much water should I drink in a heatwave?
Drink regularly before you feel thirsty, more than usual. For storage, plan at least 4–5 litres (1.1–1.3 US gal) per person per day in hot weather. Avoid alcohol and lots of caffeine.
How do I keep my home cool without air conditioning?
Close blinds, shutters and curtains on sun-facing windows during the day, keep windows shut while it is hotter outside, and open them at night to create a through-draught. Use the oven less and switch off devices that produce heat.
What are the signs of heatstroke?
According to Ready.gov: a very high body temperature (above 39.4 °C / 103 °F), red, hot and dry skin, a fast strong pulse, dizziness, confusion or loss of consciousness. Call the emergency number and cool the person while you wait.
What is the difference between heat exhaustion and heatstroke?
Heat exhaustion causes heavy sweating, paleness, cramps, tiredness, dizziness, headache and nausea; it usually improves with rest, shade and fluids. Heatstroke is a medical emergency in which the body can no longer cool itself.
Are fans useful in a heatwave?
They make you feel cooler, but in extreme heat they do not lower body temperature enough on their own. Combine them with cool showers, damp cloths, fluids and a cool room or public cooling centre.
Keep reading
- /kits/heatwave/
- How much water to store for 72 hours
- /what-to-do-in-a-power-blackout/
- Emergency preparedness with medication and medical needs