Prevent Heat Exhaustion and Heat Stroke: Signs, Treatment, Risk
Everything you need to know to protect yourself and your family from heat exhaustion and heat stroke.
Quick Reference
- Heat exhaustion: Heavy sweating, weakness, pale clammy skin, cramps, nausea. Treatable on the spot.
- Heat stroke: Hot dry red skin, no sweating, body temperature above 103°F, confusion or collapse. Call 911 immediately.
- Most at risk: Children under 5, adults over 65, outdoor workers, athletes, anyone on heart or blood-pressure medication.
- Hydration target: 1 cup of water every 20 to 30 minutes during heavy exertion in heat.
- Best protection: Shift outdoor work to before 10 a.m. or after 6 p.m. when the heat index sits in triple digits.
When the heat index pushes into the triple digits, the body’s cooling system can fail fast. Heat exhaustion and heat stroke send tens of thousands of Americans to emergency rooms every summer, and they kill more people in an average year than hurricanes, tornadoes, lightning, and floods combined, according to the U.S. Centers for Disease Control and Prevention. The Almanac has been printing summer-weather warnings since 1818. The rules below have not changed in 200 years: hydrate, time your work to the cooler hours, and know the signs.
How to Prevent Heat Exhaustion and Heat Stroke
Children under five and adults over 65 are the most vulnerable groups. So are outdoor workers, athletes practicing in summer kit, anyone taking diuretics or beta blockers, and anyone who has had heat illness in the past. The good news is that nearly every case of heat exhaustion is preventable when a few rules are followed.
- Drink water hourly, even before you feel thirsty. Thirst is a lagging signal. By the time it kicks in, you are already dehydrated.
- Shift outdoor work to the cooler hours. Start early, quit by early afternoon. The hottest part of the day in most U.S. regions is between 1 p.m. and 5 p.m.
- During vigorous sports activity like a marathon, soccer match, or football practice, drink one cup of water or a sports drink every 20 to 30 minutes.
- Wear loose, light-colored, breathable clothing. Cotton and linen breathe better than polyester. A wide-brim hat shaves several degrees off skin temperature.
- Take a 10-minute shade break every hour when working outside in extreme heat. Sit, drink, cool down.
- Never leave a child or pet in a parked car, even with the window cracked. Interior temperatures rise by 20 degrees in 10 minutes on a warm day.
- Use the buddy system. Heat illness affects judgment. A coworker or running partner notices the early signs before you do.
Signs of Heat Exhaustion
Heat exhaustion is the body’s warning that it is losing the cooling fight. Catch it here and the person almost always recovers within an hour. Miss it and it can roll into heat stroke. The signs:
- Heavy sweating
- Pale, cool, clammy skin
- Muscle cramps in the legs, arms, or stomach (caused by salt loss)
- Weakness, dizziness, or feeling faint
- Nausea or vomiting
- Fast, weak pulse
- Headache
- Body temperature elevated but typically below 103°F
How to Treat Heat Exhaustion
- Move the person to a cool or shaded place. Indoors with air conditioning is best.
- Have them sit or lie down. If their legs are cramping, lie them flat with feet raised and gently massage the cramping muscles.
- Remove shoes, socks, and any tight or excess clothing.
- Apply a cold compress to the face, neck, and underarms. A wet towel works.
- Mix a teaspoon of salt into one liter of water and have them sip it. A sports drink with sodium and potassium does the same job.
- Repeat the salt water or sports drink once an hour until the cramps stop.
- If symptoms worsen or do not improve within an hour, seek medical care.
Signs of Heat Stroke
Heat stroke is rare but life-threatening. It is what happens when the body has run out of cooling capacity. The skin actually stops sweating and the core temperature climbs fast. Without rapid cooling, heat stroke kills or causes permanent brain and organ damage.
- Skin is red, hot, and dry. Sweating has stopped.
- Body temperature is 103°F or higher
- Confusion, slurred speech, or strange behavior
- Throbbing headache
- Rapid, strong pulse
- Vomiting
- Loss of consciousness or seizure
How to Treat Heat Stroke
Call 911 immediately. While waiting for help, do the following:
- Move the person to a cool, shaded place or indoors to air conditioning.
- Lower body temperature by any means available: soak with cool water, mist with a hose, place ice packs in the armpits and groin where major blood vessels run close to the surface.
- Fan the person to speed evaporation.
- Do not give them anything to drink if they are unconscious or confused.
- If they are alert and able to swallow, sip cool water only, no salt added at this stage.
- Stay with them until paramedics arrive. Heat stroke can cause sudden seizures or cardiac arrest.
Regional Heat Risk Around the U.S.
| Region | Heat profile |
|---|---|
| Desert Southwest (AZ, NV, CA Inland) | Daytime highs over 110°F common in July and August. Dry heat hides dehydration; sweat evaporates instantly. |
| Gulf Coast and Southeast | High humidity pushes the heat index 10 to 15 degrees above the air temperature. Sweat does not evaporate; cooling efficiency drops. |
| Texas, Oklahoma, Kansas | Long stretches of 100°F+ days, especially during La Nina summers. |
| Midwest and Mid-Atlantic | Heat domes producing 4 to 7 day waves with humid nights that prevent overnight cooling. |
| Pacific Northwest | Lower frequency, higher risk: most homes lack air conditioning. The June 2021 dome killed hundreds. |
| Northern Plains and New England | Shorter heat waves but elevated risk because populations are less acclimatized. |
Frequently Asked Questions
What is the difference between heat exhaustion and heat stroke?
Heat exhaustion is the warning stage: heavy sweating, pale clammy skin, cramps, weakness. Heat stroke is the failure stage: sweating stops, the skin is hot and dry, the body temperature rises above 103°F, and the person becomes confused or unconscious. Heat exhaustion is treated on the spot. Heat stroke needs 911 immediately.
How much water should I drink in extreme heat?
During heavy exertion in heat, one cup of water or a sports drink every 20 to 30 minutes is the rule. For day-to-day life in a heat wave, aim for about one ounce of water per pound of body weight per day, split across the day. Watch the color of your urine: pale yellow means hydrated.
Are sports drinks better than water in a heat wave?
For exertion over an hour or for someone showing early heat exhaustion signs, yes. Sports drinks replace sodium and potassium lost through sweat. For light activity or daily hydration, plain water is enough. Avoid alcohol and heavily caffeinated drinks; both push fluid out of the body.
Who is most at risk for heat illness?
Children under five, adults over 65, outdoor workers, athletes, pregnant women, anyone on diuretics or blood-pressure medication, and anyone who has had heat illness before. Acclimatization matters too: a hot day in Seattle is more dangerous than a hot day in Phoenix because Pacific Northwest residents are less heat-adapted.
Can heat stroke be fatal?
Yes. Without rapid cooling and medical care, heat stroke kills. Even survivors can suffer permanent damage to the brain, heart, kidneys, and muscles. This is why heat stroke is a 911 emergency and not a wait-and-see situation.
How long does it take to recover from heat exhaustion?
Most people feel close to normal within one to two hours of resting in a cool place and hydrating. Plan to take it easy for the rest of the day and avoid heat exposure for at least 24 to 48 hours. The body is more vulnerable to a second episode in the days that follow.
Deborah Tukua
Deborah Tukua is a natural living, healthy lifestyle writer and author of 7 non-fiction books, including Pearls of Garden Wisdom: Time-Saving Tips and Techniques from a Country Home, Pearls of Country Wisdom: Hints from a Small Town on Keeping Garden and Home, and Naturally Sweet Blender Treats. Tukua has been a writer for the Farmers' Almanac since 2004.
- Deborah Tukua
- Deborah Tukua
- Deborah Tukua
- Deborah Tukua
