Extreme heat

What it is

Extreme heat is a period of unusually high heat, often with high humidity, that lasts two days or more. It kills more people in the US each year than any other weather, and the danger is greatest when nights stay hot too.

Who is at risk

Older adults, babies and young children, pregnant people, outdoor workers, people with heart, lung or kidney disease, people who take certain medicines, and anyone without air conditioning.

Get ready now

1. Find out where your nearest cooling center or air-conditioned public place is.
2. Check your air conditioning works before summer, and plan what you will do if the power goes out.
3. Ask a doctor whether any medicines in your home make heat more dangerous.
4. Cover windows that get morning or afternoon sun with drapes or shades.
5. Plan to check on older neighbors and relatives during a heat wave.
6. Learn the signs of heat exhaustion and heat stroke.

When it happens

1. Stay in air conditioning as much as you can. Fans alone may not prevent heat illness when it is very hot.
2. Drink plenty of water, even if you are not thirsty.
3. Avoid hard work outside, especially in the afternoon. Wear light, loose clothing.
4. Never leave children or pets in a parked car, even for a minute.
5. Heat stroke is an emergency: call 911 for a high body temperature, confusion, or hot, red skin. Cool the person while you wait.
6. For heat exhaustion (heavy sweating, dizziness, nausea), move to a cool place, loosen clothing and sip water.

After

1. Keep drinking water and resting; heat illness can show up later.
2. Check on people who live alone.
3. Throw out food that spoiled if the power went out.

Official sources

• Ready.gov: Extreme heat
• National Weather Service: Heat safety
• CDC: Heat and health
• American Red Cross: Heat wave safety

This guide summarises public advice. Always follow instructions from local officials and emergency services.