Prepare for a heat wave before it lands. Line up air conditioning you can reach ; if you can't, wet your skin and use a fan, since a dry fan in very hot air mostly pushes warm air around . Go in hydrated, schedule outdoor work and exercise around the heat , and ease in: adapting to heat takes about a week you haven't had yet.
The heat wave you're least ready for is the first one of the summer. Your body does adapt to heat, but slowly, so ease in rather than tough it out. About 75 to 80 percent of heat acclimatization is complete only after seven days of moderate exertion in the heat, and reaching it fully takes one to two hours a day of exertion in the heat for at least a week. Most people aren't spending that much time exercising in the heat, so for them it takes longer. Because of this, the first heat wave of the summer tends to be the most dangerous.
Air conditioning is the plan. Make sure yours is working and ready in advance if you can. And if you do not have access to AC, look for places you can go: libraries, malls, and cooling centers are all good places to check. If you cannot get to one, a fan can still help, but it is no substitute for air conditioning. Portable electric fans don't cool air, they move it around and keep you cool by helping your sweat evaporate. So wet your skin first, laying a damp cloth or towel on it or misting yourself with a spray bottle, and then point the fan at you. Without that, a fan in very hot air mostly pushes warm air around.
You cannot drink your way out of a heat wave. Going in hydrated still helps: pay attention to your body and drink when you're thirsty. But unfortunately, hydration alone cannot always prevent heat from building up. Move hard effort off the middle of the day. If you are outside, try to stay in the shade, since being in direct sunlight can add 15 to 20°F more to the temperature. And ask your pharmacist whether your prescriptions change how you handle heat, because many medicines can leave you more dehydrated or overheated on hot days.
Don't forget to plan for the people who cannot plan for themselves. Older adults, young children, and people with chronic medical conditions are at high risk of heat illness and even potentially death, so check on your family, friends, and neighbors and have someone do the same for you. And this affects your pets too, so make sure they have plenty of water and access to the same cool places you do.
Sources
- [1] Protect Yourself From the Dangers of Extreme Heat (Climate and Health). Accessed August 6, 2026. https://www.cdc.gov/climate-health/php/resources/protect-yourself-from-the-dangers-of-extreme-heat.html
- [2] Excessive Heat Events Guidebook (EPA 430-B-06-005, June 2006). Accessed August 6, 2026. https://www.epa.gov/sites/default/files/2016-03/documents/eheguide_final.pdf
- [3] Wilderness Medical Society / Wilderness & Environmental Medicine. Wilderness Medical Society Clinical Practice Guidelines for the Prevention and Treatment of Heat Illness: 2024 Update. 2024. Accessed August 5, 2026. https://doi.org/10.1177/10806032241227924
- [4] Heat Waves in the United States: Mortality Risk during Heat Waves and Effect Modification by Heat Wave Characteristics in 43 U.S. Communities (Anderson & Bell, Environ Health Perspect 2011). Accessed August 6, 2026. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3040608/
- [5] Journal of the Mississippi State Medical Association (JMSMA). Low-cost Options for Keeping Cool During Extreme Hot, Humid Weather. 2022. Accessed August 6, 2026. https://jmsma.scholasticahq.com/article/37291-low-cost-options-for-keeping-cool-during-extreme-hot-humid-weather
- [6] US National Park Service. Hike Smart — Grand Canyon National Park. Accessed August 5, 2026. https://home.nps.gov/grca/planyourvisit/hike-smart.htm
- [7] US Centers for Disease Control and Prevention. About Heat and Your Health — CDC Heat Health. July 20, 2026. Accessed August 6, 2026. https://www.cdc.gov/heat-health/about/index.html
About the author
Dr. Colin Little
MD, FAWM, Chief Medical Officer, GOES Health
- Board Certified Emergency Physician
- Fellow of the Academy of Wilderness Medicine (FAWM)
- Wilderness Medicine Fellowship, University of Utah
- Emergency Medicine Residency and Chief Resident, Stanford / Kaiser
- Doctor of Medicine, University of Arizona College of Medicine – Phoenix