When temperatures climb, the goal is simple: keep your body’s core temperature from rising faster than it can cool itself down. That means adjusting how you drink, dress, move, and cool your living space. Most heat-related illness is preventable with straightforward changes, but the margin for error shrinks as the thermometer rises. Here’s what actually works.
Drink Before You’re Thirsty
Your body cools itself primarily through sweat, and sweat is mostly water and sodium. During heavy heat exposure, you can lose enough fluid to impair that cooling system well before you notice thirst. The CDC recommends drinking about 1 cup (8 ounces) of water every 15 to 20 minutes when you’re active in the heat, which works out to roughly 24 to 32 ounces per hour. There’s also an upper limit: don’t exceed 48 ounces (1.5 quarts) per hour, because drinking too much water too fast can dangerously dilute your blood sodium levels.
Plain water works fine for short stretches, but if you’re outside for hours, whether working, exercising, or just enduring a home without air conditioning, you need to replace salt too. People working in moderately hot conditions (around 95°F with 50% humidity) for a full day can lose 5 to 6 grams of sodium through sweat, equivalent to 12 to 15 grams of table salt. That’s far more than most people realize. Sports drinks help, but many are heavy on sugar and light on sodium. Salty snacks, broth, or electrolyte tablets added to water are practical ways to keep up.
Cool Your Home Without AC
If you don’t have air conditioning, cross ventilation is your best tool. Open windows or doors on opposite sides of a room so air can flow in one side and out the other. This works best when one opening faces the direction the wind is coming from. Keep the path between the two openings as clear of furniture and obstacles as possible, and aim for rooms where the openings are within about 20 feet of each other. On still days, place a fan near one opening to force the airflow.
However, fans have a hard limit. Once the air temperature exceeds roughly 95°F (35°C), which is close to the temperature of your skin, a fan actually makes things worse. Instead of cooling you through evaporation, it blows air that’s hotter than your body across your skin, increasing heat gain. At that point, switch strategies: dampen a towel or shirt and drape it on your skin, take cool showers, or apply cold water to your wrists, neck, and forehead. These work because they cool through direct contact rather than relying on air movement.
Other basics that add up: close blinds or curtains on sun-facing windows during the day, avoid using the oven or stove, and move your activity to the lowest floor of your home, since heat rises. If your home simply can’t stay cool enough, public libraries, malls, and designated cooling centers are worth the trip.
Dress for Evaporation, Not Just Comfort
Loose-fitting, lightweight clothing gives sweat room to evaporate, which is the whole point of sweating. Tight clothing traps moisture against your skin and slows that process. Fabrics matter too. Lightweight cotton breathes well but dries slowly. Synthetic moisture-wicking fabrics pull sweat away from your skin and dry faster, which keeps the cooling cycle going.
Color is a tradeoff. Light-colored clothing reflects more solar radiation and absorbs less heat, which keeps you cooler in direct sun. But darker colors block far more ultraviolet radiation: a dark grey cotton shirt can block nearly all UV (UPF 98), while the same shirt in white blocks much less (UPF 9). If you’re worried about sunburn and heat, a loose, light-colored UPF-rated shirt gives you both benefits. A wide-brimmed hat shades your head and neck, where blood vessels sit close to the surface and absorb heat quickly.
Adjust When and How You Move
The single easiest way to avoid heat illness is to shift outdoor activity to early morning or evening, when temperatures and sun intensity are lowest. If you have to be outside during peak heat (typically 10 a.m. to 4 p.m.), take breaks in shade every 15 to 20 minutes and reduce your intensity. Your body generates substantial internal heat during exercise or physical labor, and in high temperatures, it simply can’t shed that heat fast enough.
Give yourself time to acclimate, too. If you’re not used to the heat, whether because of travel, a sudden heat wave, or the start of summer, your body needs roughly 7 to 14 days of gradual exposure to become efficient at cooling itself. During that adjustment period, you sweat out more sodium and fatigue faster, so go easier than you think you need to.
Know Who’s at Higher Risk
Young children and older adults are more vulnerable because their bodies regulate temperature less efficiently. Older adults also have a reduced thirst response, meaning they can become significantly dehydrated without feeling the urge to drink.
Several common medications also interfere with your body’s cooling system. Diuretics (often prescribed for blood pressure) increase fluid loss and can deplete electrolytes. Antihistamines like diphenhydramine reduce sweating, which is your primary cooling mechanism. Some psychiatric medications also impair the body’s ability to regulate temperature. If you take any of these, you don’t need to stop them in the heat, but you do need to be more aggressive about staying cool and hydrated, and more alert to early warning signs.
Recognize Heat Exhaustion Early
Heat exhaustion is your body waving a yellow flag. Core temperature rises to between 101°F and 104°F, and symptoms include heavy sweating, pale or clammy skin, muscle cramps, headache, nausea, dizziness, and a fast heartbeat. At this stage, the situation is reversible. Move to a cool place, drink water, apply cold compresses to your skin, and rest. Most people recover within 30 to 60 minutes.
The critical thing is recognizing when heat exhaustion tips into heat stroke, because heat stroke is a medical emergency. The defining features are a core temperature above 104°F (40°C), confusion or slurred speech, and often a stop in sweating entirely. The skin becomes hot, dry, and red instead of pale and clammy. Seizures, hallucinations, aggression, and loss of consciousness can follow. If someone shows these signs, call 911 immediately and begin cooling them as aggressively as possible: immerse them in cold water if available, pack ice around the neck, armpits, and groin, or drape them in cold wet towels and keep rotating them. Cold water immersion cools the body three to four times faster than towel methods and produces the best outcomes.
A Quick Checklist for Hot Days
- Hydrate proactively: 8 ounces of water every 15 to 20 minutes during heat exposure, with electrolytes for longer stretches.
- Time your activity: Move exertion to early morning or evening when possible.
- Cool your space smartly: Use cross ventilation below 95°F; switch to wet towels and cold water above it.
- Dress light and loose: Light colors in the sun, moisture-wicking fabrics, and a hat.
- Watch for red flags: Confusion, dry skin, and stopped sweating mean heat stroke. Cool immediately and call for help.
- Check on others: Older adults, young children, and people on certain medications may not recognize their own symptoms.