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People cooling off in a public park fountain on a hot day.

Extreme Heat

Words to Know

Am I at Risk?

What Can I Do?

Learn More

Some days are hot, and then some days are really hot! Extreme heat happens when temperatures soar above 90°F for several days with lots of humidity. When it’s this hot, your body has to work extra hard to stay cool—which can be dangerous if you’re not careful.

Did you know that extreme heat causes more deaths than any other kind of weather? That’s why it’s important to know how to stay safe and beat the heat!

Words to Know

Heat Wave - A heat wave is a period of unusually hot weather that typically lasts two or more days. To be considered a heat wave, the temperatures must be unusual for a given area. For example, a few days of 95-degree summer days in Houston, Texas may not be considered a heat wave because summers are usually quite warm there. But if Maine, which is usually cooler in the summer, had a few days at that temperature it might be considered a heat wave.

Extreme Heat Warning - A warning issued when extremely dangerous heat conditions are expected or is already happening. It means you should avoid outdoor activities, especially during the heat of the day. If you must be outside, be sure to drink plenty of water and take frequent breaks in the shade. Stay indoors in an air-conditioned space as much as possible, including overnight. Check on family and neighbors, and make sure to bring your pets inside. 

Humidity - Humidity is a way of explaining how much water vapor – gas - is in the air. When there’s more water vapor in the air and it’s hot outside, it can make it you feel uncomfortable because your sweat can’t evaporate.

Extreme Heat Watch - A warning issued when extreme heat is possible. It means you should plan to cancel outdoor activities and pay attention to the weather on TV or the radio. If you do not have air conditioning, locate the nearest place you can go to stay cool, or discuss staying with nearby family or friends who have air conditioning.

Heat Advisory - A warning issued when it will be hot, but not as hot as during a period of extreme heat. It means you should consider postponing or rescheduling outdoor activities, especially during the hottest part of the day. If you will be outside, be sure to drink plenty of water and take frequent breaks in the shade. Stay in a cool place, especially during hot parts of the and evening.

Am I at Risk?

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Where you live matters when it comes to extreme heat. If you live somewhere that doesn’t usually have multiple days in a row of 90 degrees or higher, a few days of high heat and humidity would be considered extreme heat.  Extreme heat makes your body works extra hard to maintain a normal temperature, which can make you very sick.

What can I do?

Before

A dizzy child with red skin and a fever, from extreme heat.
  • Learn to recognize the signs of heat illness. If you or a friend feel sick, have muscle cramps, feel weak or dizzy tell a grown up right away. Go somewhere cool, drink some water and rest.
  • Find places in your community where you can go to get cool. This could be a library, shopping mall or community center. Contact your local health department to find cooling options in your area.

During

Kid drinking water in extreme heat, wearing loose fitting, light clothing.
  • Drink plenty of water.
  • Wear loose, lightweight, light-colored clothing. Wear a hat wide enough to protect your face. 
  • Take cool showers or baths to cool down.
  • Never leave people or pets in a car on a warm day.
  • If you don’t have air conditioning at home, find somewhere to stay cool. This could be a library, shopping mall or community center.
  • Keep window blinds and shades closed to keep the heat out.
  • If you’re outside, find shade.
  • Avoid playing outside or doing sports during midday heat.
  • Check on family members, friends and neighbors. This is especially important for older adults and people who spend most of their time home alone.
  • Watch for heat related illnesses and tell a grown up right away if you or someone you know feels sick.
  • Keep your pets safe. If they are outside, make sure they have plenty of cool water and access to comfortable shade. Asphalt and dark pavement can be very hot to your pet’s feet.

Learn More

Last Updated: 03/21/2025

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