Extreme Heat Safety: Heat Exhaustion vs. Heat Stroke Symptoms and How to Keep Your Home Cool

Summers are getting hotter, heat waves are lasting longer, and nights aren't cooling down the way they used to. Extreme heat isn't just uncomfortable. According to the National Weather Service, heat kills more people in the US than any other weather hazard, more than hurricanes, floods or tornadoes. Recent years have set grim records for heat-related deaths.

The heartbreaking part is that almost every heat-related death is preventable. Knowing the warning signs, keeping your home cool and looking out for vulnerable people can genuinely save lives. Here's what you need to know before the next heat wave.

Why extreme heat is dangerous

Your body cools itself mainly by sweating. When sweat evaporates from your skin, it carries heat away. But in very hot or humid weather, that system can get overwhelmed:

• High temperatures mean your body gains heat faster than it can lose it.
• High humidity means sweat doesn't evaporate well, so it can't cool you.
• Hot nights mean your body never gets a chance to recover.

As your core temperature rises, you can develop heat illness, which ranges from mild cramps to life-threatening heat stroke.

Who is most at risk from extreme heat?

Anyone can get heat illness, but risk is higher for:

• Older adults, especially over 65, whose bodies regulate temperature less efficiently and who may not feel thirsty
• Babies and young children
• People with chronic conditions such as heart disease, lung disease, diabetes, kidney disease or obesity
• People taking certain medicines (see below)
• Pregnant people
• People who live alone or are socially isolated
• People without air conditioning
• Outdoor workers and athletes
• People experiencing homelessness
• People with mental health conditions or dementia

Medications that increase heat risk

Some medicines make it harder for your body to handle heat or cause you to lose fluids, including:

• Diuretics ("water pills")
• Some blood pressure medicines, such as beta blockers
• Some antidepressants and antipsychotics
• Antihistamines and other anticholinergic medicines
• Stimulants, including some ADHD medications

Don't stop any medicine on your own. Ask your doctor or pharmacist whether yours increase heat risk, and how to stay safe.

Heat exhaustion vs. heat stroke: know the signs

Heat exhaustion

Symptoms:

• Heavy sweating
• Cold, pale, clammy skin
• Fast, weak pulse
• Nausea or vomiting
• Muscle cramps
• Tiredness or weakness
• Dizziness
• Headache
• Fainting

What to do:

• Move to a cool place
• Loosen clothing
• Put cool, wet cloths on your body or take a cool bath
• Sip water
• Get medical help if you're vomiting, symptoms get worse or last longer than an hour

Heat stroke: a medical emergency

Symptoms:

• High body temperature (103°F / 39.4°C or higher)
• Hot, red, dry or damp skin
• Fast, strong pulse
• Headache
• Dizziness
• Nausea
• Confusion
• Losing consciousness

What to do:

• Call 911 right away. Heat stroke can be fatal.
• Move the person to a cooler place
• Help lower their temperature with cool cloths, a cool bath, or ice packs on the neck, armpits and groin
• Do not give them anything to drink if they're confused or unconscious

The key difference: in heat exhaustion, people are usually still sweating and alert. In heat stroke, confusion is a red flag. When in doubt, call 911.

Check the heat forecast: the CDC HeatRisk tool

In 2024, the CDC and National Weather Service launched HeatRisk, a color-coded forecast that tells you how dangerous heat will be in your area over the next seven days and who's at risk. It considers how unusual the heat is for your location and how long it lasts, including overnight. You can check it on the CDC or National Weather Service websites.

How to keep your home cool in a heat wave

Block the sun

• Close blinds, curtains and shades during the day, especially on south- and west-facing windows. Light-colored or reflective window coverings work best.
• Exterior shading, like awnings, shade sails and trees, stops heat before it reaches the glass.

Use cooler night air

• If it cools down at night, open windows in the evening and early morning to let cool air in, and close them as the day heats up.
• Create a cross breeze by opening windows on opposite sides of your home.
• Place a fan in a window blowing out to push hot air outside.

Avoid adding heat

• Skip the oven and stove on hot days. Eat cold meals, use a microwave, slow cooker or outdoor grill.
• Run the dishwasher and dryer at night, or air-dry laundry.
• Turn off unnecessary lights and electronics.

Use air conditioning wisely

Air conditioning is the most protective factor against heat illness. If you have it:

• Set it to a comfortable temperature and keep doors and windows closed
• Clean or replace filters
• Use it especially in the bedroom at night

Fans: helpful, with limits

Fans help when temperatures are moderate. But the CDC warns that when it's very hot (in the high 90s Fahrenheit or above), electric fans may not prevent heat-related illness. In that heat, they can even blow hot air over you. Cool showers, damp cloths and spending time somewhere air-conditioned are better.

Where to cool off if your home is too hot

• Cooling centers: many cities open public cooling centers during heat waves. Call 211 or check your city's website.
• Libraries, malls, community centers and movie theaters
• A friend or family member's air-conditioned home
• Even a few hours a day in air conditioning can help your body recover.

How to sleep in the heat

Hot nights are dangerous because your body can't recover, and heat disrupts sleep. Try:

• A cool shower before bed
• Lightweight cotton or linen sheets and pajamas
• A damp cloth on your neck or wrists
• Sleeping on the lowest floor of your home, where it's coolest
• A frozen water bottle wrapped in a towel near the bed
• Keeping the bedroom shaded all day

See how much sleep adults need for more sleep habits.

Stay hydrated (the right way)

• Drink water regularly, even before you feel thirsty. Older adults especially shouldn't wait for thirst.
• Avoid sugary drinks and too much alcohol, which can worsen dehydration.
• If you're sweating heavily for long periods, replace salt and minerals with food or a sports drink.
• If your doctor limits your fluids, ask how much to drink during hot weather.

Our guide to how much water you need has more.

Staying safe outdoors in hot weather

• Plan outdoor activities for early morning or evening
• Wear lightweight, loose, light-colored clothing and a wide-brimmed hat
• Wear sunscreen; sunburn makes it harder for your body to cool down
• Take frequent breaks in the shade
• Build up gradually if you're not used to the heat (acclimatization takes about one to two weeks)
• Stop immediately if you feel dizzy, weak or confused

Never leave anyone in a parked car

Temperatures inside a parked car can climb dangerously fast, rising roughly 20°F in just 10 minutes, even with windows cracked. Never leave children, older adults or pets in a parked car, even briefly. Check the back seat every time you get out.

Pets and extreme heat

Pets can overheat quickly. Walk dogs in the cooler parts of the day, test pavement with your hand (if it's too hot for you to hold for seven seconds, it's too hot for paws), and make sure they always have shade and fresh water.

Heat and mental health

Extreme heat doesn't only affect the body. Research has linked hot weather with more emergency visits for mental health conditions, worse sleep, more irritability and higher rates of conflict. If heat leaves you feeling low or anxious, you're not imagining it. Be gentle with yourself and lean on cooling, rest and connection.

Check on your neighbors

Social isolation is one of the biggest risk factors in heat deaths. During heat waves, check on older neighbors, relatives and people who live alone, at least twice a day if possible. A quick call or knock could save a life. Building those neighborhood connections before summer is a gift to everyone. See loneliness and health.

Make a heat plan before summer

• Know where your nearest cooling center is
• Service your air conditioner or fans
• Put up reflective window coverings
• Talk to your doctor about your medicines
• Make a list of people to check on
• Sign up for local weather alerts

Frequently asked questions about extreme heat

What temperature is too hot to be outside?

It depends on humidity, sun, your health and how used to heat you are. Use the CDC's HeatRisk tool and the heat index, and take extra care when the heat index is above 90°F.

How do I know if it's heat exhaustion or heat stroke?

Confusion, a very high temperature or loss of consciousness point to heat stroke. Call 911.

Do cold showers help in a heat wave?

Yes. Cool (not ice-cold) showers or baths are an effective way to lower body temperature.

Your surroundings shape your health. See how your environmental wellness compares to the other seven dimensions with our free 2-minute quiz.