Extreme Heat Preparedness

Extreme heat is the most lethal weather hazard in the United States, deadlier than any storm, and it is becoming more common. The National Weather Service issues Heat Advisories, Excessive Heat Watches, and Excessive Heat Warnings, but the harm starts before the official warnings and lasts after the air cools. Ready.gov treats heat preparedness as a set of habits: stay cool, stay hydrated, stay informed, and check on the people most at risk. This guide covers how to prepare your home for heat, how to protect vulnerable household members, and what to do when the heat is dangerous and the power fails too.

Know who is most at risk

Heat does not affect everyone equally. The CDC identifies the people most at risk as older adults, infants and young children, people with chronic conditions, people who work or exercise outdoors, and people who are socially isolated or cannot afford air conditioning. Medications — diuretics, beta-blockers, some antidepressants — can change how the body regulates heat, so talk to a clinician about heat exposure if anyone in the household takes them. The plan is built around protecting these people first, because they are the ones a heat wave can hospitalize or kill.

Check on neighbors during a heat wave, especially older adults who live alone. The Red Cross recommends calling or visiting at least twice a day during extreme heat. Do not assume someone is fine because you have not heard otherwise. The people most at risk are often the people least likely to ask for help, and the plan includes them.

Prepare the home for a heat wave

The goal is to keep heat out before it builds. Close windows and shades during the day, especially on the sunny side, and open them at night if the air is cooler. Use curtains, blinds, or shades to block direct sun. The CDC recommends using attic fans or whole-house fans at night if the air is cooler outside. If you have air conditioning, set it to a comfortable level and keep the filters clean so it runs efficiently. A window unit in one room can be the difference between a survivable heat wave and a dangerous one.

If you do not have air conditioning, identify a nearby cooling center — a library, mall, or community center — and plan to go there during the hottest hours. Many cities open cooling centers during heat warnings; find yours before you need it. Keep a list of them. The plan is to have somewhere cool to go before the heat becomes an emergency.

Stay cool, hydrated, and informed

Drink water before you are thirsty, because thirst is a sign you are already behind. The CDC recommends avoiding sugary, alcoholic, and very cold drinks, which do not hydrate as well. Wear loose, light-colored clothing. Take cool showers or baths. Never leave anyone — a child, an older adult, a pet — in a parked car, even with the windows down; the National Weather Service notes that car interiors can reach lethal temperatures in minutes. Check the heat index, not just the temperature, because humidity makes heat more dangerous.

Pay attention to the warning signs of heat illness. Heat exhaustion includes heavy sweating, weakness, nausea, and dizziness; move the person to a cool place, give water, and cool the body with wet cloths. Heat stroke is a medical emergency: high body temperature, no sweating, confusion, or unconsciousness. Call 911 for heat stroke and cool the person with whatever you have while you wait. Knowing the difference can save a life.

When the power fails during a heat wave

A power outage during extreme heat is the most dangerous combination, because the cooling that was protecting your household stops. Move to the coolest room, usually the lowest floor away from the sun. Use battery fans and wet cloths. Stay hydrated. If your home becomes dangerously hot, go to a cooling center or a public building with air conditioning — do not wait it out if anyone is showing signs of heat illness. The CDC is clear: the risk of heat illness can be fatal, and waiting is not a plan.

If you use a generator for a window AC unit, run it outdoors and far from windows, because carbon monoxide kills even during a heat wave. Keep medications that need refrigeration in a cooler with ice if the power is out, and talk to your pharmacist about how long they stay safe at room temperature. The heat plan and the power plan overlap, and the overlap is where the danger is.

After the heat wave

Heat can linger in the body after the air cools, so keep hydrating and watch for delayed heat illness, especially in older adults and children. Open windows at night once the air drops below the indoor temperature. Run fans to ventilate hot rooms. Check on neighbors again. The recovery from a heat wave is when the plan that kept the household cool pays off, and when the check-ins on vulnerable neighbors matter most.

Review your heat plan each spring before the first heat wave. Clean the AC filters, identify the cooling centers, and confirm the list of people to check on. The heat that gives days of warning is the one you can plan for, and the plan that is in place before the first advisory is the one that works.

This is planning guidance, not emergency advice. In an emergency, call 911. See a mistake? Report it.

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