Extreme Heat Checklist + Heat Wave Safety Kit

Build your heat wave kit

A heat kit is small and mostly lives in the kitchen and the car. It is built around three questions: how the household stays hydrated, how it cools down if the air conditioning cannot keep up or the power goes out, and how you look after the people and medicines heat affects most. If stored water is new to you, our emergency water storage guide covers amounts and containers. Tap each item to check it off; progress is saved on this device.

Extreme heat response: before the season through after the heat breaks

Heat usually gives you notice, and the National Weather Service's alerts are built to use it. A watch is your cue to arrange things, an advisory to slow down, a warning to stay somewhere cool through the night. The steps below follow that order.

1. 1

   Before the season

   Find your nearest cooling center and write it down: libraries and shopping malls often serve, and 2-1-1 or your local health department can tell you where they are. Keep your home cooler with window reflectors, insulation and, if you can, an air conditioner; the Low Income Home Energy Assistance Program (LIHEAP) can help with cooling costs. Ask your doctor about any medicines that raise heat risk and how to store them, and make a list of the people you will check on.

2. 2

   When an Extreme Heat Watch is issued

   A watch means conditions are favorable for an extreme heat event, but its timing is still uncertain. Plan to suspend major outdoor activities if a warning follows. If you do not have air conditioning, locate the nearest cooling center or arrange to stay with family or friends who have it. Charge phones and battery packs, freeze ice packs, and restock water and electrolytes.

3. 3

   When a Heat Advisory is issued

   An advisory means dangerous heat that is not expected to reach warning criteria. Consider postponing outdoor activities, especially during the heat of the day. If you must be outside, drink plenty of water and take frequent breaks in the shade. Stay in a cool place, especially during the heat of the day and evening, and start your check-in calls.

4. 4

   When an Extreme Heat Warning is issued

   A warning means extremely dangerous heat is expected or occurring. Avoid outdoor activities, especially during the heat of the day. Stay indoors in an air-conditioned space as much as possible, including overnight, and go to a cooling center if your home does not have air conditioning. Check on family and neighbors, and watch everyone for signs of heat illness. Heat stroke is an emergency: call 911.

5. 5

   After the heat breaks

   Keep checking on older relatives and neighbors until temperatures return to normal. If the power went out, check your refrigerated medicines and ask your pharmacist or doctor before using any that went warm. Restock water, electrolytes and batteries, and note what did not work so the plan is better next time.

Heat Advisory vs Extreme Heat Watch vs Extreme Heat Warning

Ready.gov defines extreme heat as a period of high heat and humidity with temperatures above 90 degrees for at least two to three days, and the National Weather Service describes a heat wave as abnormally hot weather generally lasting more than two days.

The National Weather Service issues three heat alerts. On March 4, 2025 it renamed two of them: the Excessive Heat Watch became the Extreme Heat Watch, and the Excessive Heat Warning became the Extreme Heat Warning. The Heat Advisory is still issued under that name. Older apps and articles may use the old names; they mean the same thing.

Heat exhaustion vs heat stroke: signs and what to do

Knowing the difference between heat illnesses tells you whether you are cooling someone down and getting them checked, or calling 911. The CDC calls heat stroke the most serious heat-related illness: the body can no longer control its temperature, and it needs emergency treatment.

One detail is easy to miss. Heat stroke can come with hot, dry skin or with heavy sweating, so sweating does not rule it out. Confusion, slurred speech, a seizure or passing out in the heat are signs of heat stroke: call 911.

This table follows the CDC and the National Weather Service. It is a guide to first aid, not a substitute for medical care.

Who is most at risk in a heat wave

Anyone can get sick from heat, but some people are more likely to, and several of them may live in your house or on your street. The CDC names these groups:

If someone you love is on this list, the most useful thing you can do is visit. The CDC's caretaker checklist suggests seeing them at least twice a day during a heat wave and asking four things: are they drinking enough water, do they have access to air conditioning, do they know how to keep cool, and do they show signs of heat stress? Our guide to storing temperature-sensitive medicines covers the medicine side of the same plan.

Cooling centers, no air conditioning, and power outages

Staying in air conditioning, overnight included, is the heart of the Weather Service's advice during an Extreme Heat Warning. That makes two situations the ones to plan for: a home without it, and a home that loses it when the power goes out.

Never leave children or pets in a parked car

The National Weather Service puts it plainly: it is never safe to leave a child, disabled person or pet locked in a car, even in winter. A parked car heats up fast even on a mild day in the 70s. The CDC notes the temperature inside can rise almost 20°F within the first 10 minutes, and a cracked window does not stop it.

A routine protects better than a good intention on a busy day:

• Keep a stuffed animal in the car seat, and move it to the front seat when your child is buckled in.
• Check that everyone is out every time you leave the car, including a child who fell asleep.
• Lock car doors and trunks, even in your own driveway, and keep keys out of children's reach so they cannot climb in and become trapped.
• Touch the car seat and buckle before strapping a child in, to make sure they are not too hot.

Pets need the same care. Leave them at home rather than in the car, and give them plenty of fresh, cool water in a shaded spot.

Heat alerts and your phone

Wireless Emergency Alerts are the loud, government-sent alerts that arrive with a special tone and vibration, both repeated twice. The warnings the National Weather Service sends that way cover tornadoes, destructive thunderstorms, serious flash floods, hurricanes, typhoons, storm surge, extreme wind, dust storms, snow squalls and tsunamis. Heat is not on that list. Local and state public safety agencies can also send WEA messages, but do not count on your phone to tell you a heat wave is coming.

So for heat, bring the alerts to you:

• Check the forecast and the NWS HeatRisk map when a hot week is coming.
• Follow local radio and television, including NOAA Weather Radio, as the National Weather Service advises during extreme heat.
• Let BeAware monitor your address for official heat advisories, watches and warnings.

Keep WEA switched on anyway. No signup is required, but alerts can be turned off in phone settings, and WEA still carries the tornado, flash flood and other warnings listed above. On an iPhone, go to Settings, Notifications, then Government Alerts. On Android, go to Settings, Notifications, then Wireless Emergency Alerts.

Extreme heat preparedness FAQ

Sources

The health and safety guidance on this page follows the CDC, the National Weather Service and Ready.gov. Where our wording differs from theirs, theirs is correct.

• Heat-related Illnesses — CDC, National Institute for Occupational Safety and Health

  Supports: the heat illness table: "Heat stroke is the most serious heat-related illness"; its symptoms (confusion, altered mental status, slurred speech; loss of consciousness; "hot, dry skin or profuse sweating"; seizures; very high body temperature) and first aid ("Call 911 for emergency medical care", stay with the person, move them to a shaded, cool area, remove outer clothing, cool them quickly with a cold water or ice bath if possible, wet skin, cold wet cloths or ice on "the head, neck, armpits, and groin", circulate the air); heat exhaustion as "the body's response to an excessive loss of water and salt, usually through excessive sweating", its symptoms and first aid (medical evaluation, "Call 911 if medical care is unavailable", liquids, remove unnecessary clothing including shoes and socks, cold compresses, "frequent sips of cool water"); and heat cramps (sports drinks "every 15 to 20 minutes", "Avoid salt tablets", get medical help for heart problems, a low sodium diet, or cramps that do not subside within 1 hour).

• About Heat and Your Health — Centers for Disease Control and Prevention

  Supports: the fan rule ("Use fans, but only if indoor temperatures are less than 90°F. In temperatures above 90°F, a fan can increase body temperature"); finding air conditioning by dialing 2-1-1 or contacting your local health department or emergency management agency; checking on family, friends, neighbors and pets; carrying a water bottle, limiting drinks high in sugars, sodium, caffeine and alcohol, and the urine-color check; the medicine plan ("Many medicines can make you dehydrated or overheated on hot days"; "Don't stop or change your medicines until you talk to your doctor"; some "need to be kept out of hot places"); "Heat can cause power outages. Have a plan for what to do with refrigerated medications and electronic medical devices"; the heat action plan; and the CDC HeatRisk Dashboard by ZIP code.

• People at Increased Risk for Heat-Related Illness — Centers for Disease Control and Prevention

  Supports: the higher-risk groups: older adults (65+), infants and children, people with chronic conditions, people without air conditioning, athletes, outdoor workers, and pregnancy.

• Heat and Older Adults (Aged 65+) — Centers for Disease Control and Prevention

  Supports: that older adults "do not adjust as well as young people to sudden changes in temperature" and are "more likely to take prescription medicines that affect the body's ability to control its temperature or sweat"; asking a doctor how much to drink if fluids are limited; not relying on a fan; and the caretaker checklist (visit "at least twice a day" and ask the four questions).

• Heat and Chronic Conditions — Centers for Disease Control and Prevention

  Supports: that people with chronic conditions "may be less likely to sense and respond to changes in temperature" and "may be taking medications that can make the effect of heat worse", and that "heart disease, mental illness, poor blood circulation, and obesity are risk factors for heat-related illness."

• Heat and People without Air Conditioning — Centers for Disease Control and Prevention

  Supports: that fans "won't prevent heat-related illness" when it is really hot; the buddy system; cool showers or baths; using the stove and oven less; "even a few hours spent in air conditioning can help"; and LIHEAP for help with costs.

• Infants and Children and Heat — Centers for Disease Control and Prevention

  Supports: that infants and young children "rely on others to keep them cool and hydrated"; never leaving children in a parked car; "temperatures inside the car can rise almost 20 degrees Fahrenheit within the first 10 minutes, even with a window cracked open"; the stuffed-animal reminder; and checking that everyone is out of the car.

• Heat and Outdoor Workers — Centers for Disease Control and Prevention

  Supports: that outdoor workers "are more likely to become dehydrated and get heat-related illness"; acclimatization, a brimmed hat, sunscreen, and scheduling tasks earlier or later; and "If you feel faint or weak, STOP all activity and get to a cool place."

• Heat and Pets — Centers for Disease Control and Prevention

  Supports: never leaving pets in a parked car, and providing plenty of fresh water in a shady area.

• Understanding Heat Alerts — National Weather Service

  Supports: the three alert definitions and the actions for each (Extreme Heat Warning: "extremely dangerous heat conditions are expected or occurring"; Extreme Heat Watch: "conditions are favorable for an extreme heat event but its occurrence and timing is still uncertain"; Heat Advisory: "dangerous heat conditions that are not expected to reach warning criteria"), including staying in air conditioning "including overnight" and arranging to stay with people who have it; and that local offices set when alerts are issued with local partners.

• National Weather Service revamps Heat Watch and Heat Warning products — National Weather Service

  Supports: the rename: on March 4, 2025, Excessive Heat Watches became Extreme Heat Watches and Excessive Heat Warnings became Extreme Heat Warnings.

• During a Heat Wave — National Weather Service

  Supports: the heat wave definition ("a period of abnormally hot weather generally lasting more than two days"); grid strain ("Transmission capacity across electric lines is reduced during high temperatures, further straining the electrical grid"); following local radio and television, including NOAA Weather Radio; "Do not direct the flow of portable electric fans toward yourself when room temperature is hotter than 90°F"; salt tablets only if a physician specifies; "Sunburn reduces your body's ability to dissipate heat"; fluid-restricted diets; and the vehicle tips (mild days "in the 70s", touching the safety seat first, locking doors and trunks, keys out of reach).

• Heat-Related Illness — National Weather Service

  Supports: heat stroke first aid ("Call 911 or get the victim to a hospital immediately. Heat stroke is a severe medical emergency") and its "body temperature above 103°F" sign, and seeking immediate medical attention for heat exhaustion "if the person vomits, symptoms worsen or last longer than 1 hour".

• Heat Safety Tips and Resources — National Weather Service

  Supports: "It is NEVER safe to leave a child, disabled person or pet locked in a car, even in the winter", and locking cars in your own driveway when there is a toddler at home.

• NWS HeatRisk — National Weather Service, Weather Prediction Center

  Supports: that HeatRisk "is supplementary to official NWS heat watches, warnings, and advisories", its 0 to 4 scale from "Little to no risk" to "Extreme", and that it weighs how unusual the heat is, how long it lasts day and night, and CDC health data.

• Heat Index — National Weather Service

  Supports: the heat index definition ("how hot it really feels when relative humidity is factored in with the actual air temperature") and that "Exposure to full sunshine can increase heat index values by up to 15°F."

• Weather warnings on the go! (Wireless Emergency Alerts) — National Weather Service

  Supports: the list of warnings NWS sends as WEA (tsunami, tornado, destructive severe thunderstorm, considerable or catastrophic flash flood, hurricane, typhoon, storm surge, extreme wind, dust storm, snow squall), which does not include heat; that local and state public safety agencies also send WEA; "No signup is required!"; and the "special tone and vibration, both repeated twice."

• Extreme Heat — Ready.gov

  Supports: the definition of extreme heat as "a period of high heat and humidity with temperatures above 90 degrees for at least two to three days"; cooling centers such as libraries and shopping malls; weatherizing with insulation and window reflectors; LIHEAP; "Never leave people or pets in a closed car on a warm day"; pets needing "plenty of cool water and access to comfortable shade"; checking on family members, older adults and neighbors; and heat stroke signs including a body temperature above 103°F.

Deep dives from our article library

These articles go deeper on the parts of a heat plan that overlap with other emergencies: outages, medicines, water and life without power.

Complete Power Outage Survival Guide

What helps keep a household safe when the power goes out, including how to handle a summer outage in the heat.

Emergency Medications: How to Store and Rotate Prescription Drugs

A rotation system for prescriptions, with a section on temperature-sensitive medicines and what to do when refrigeration fails.

Emergency Water Storage Guide

How much water your household needs, which containers to use, and how to store and rotate it somewhere cool.

Non-Electric Alternatives for Daily Life

Manual ways to keep a household running without power, including a section on heating and cooling.