Beat the Heat: Prevent Heat-Related Illnesses

Woman walking along dirt trail
Be prepared for the high temperatures during your park visit.

NPS Photo

Summer inspires us all to go outside and explore the great outdoors. High temperatures and the risk of heat illness can happen in any national park environment whether its an urban, historical, mountainous, or desert park. Be prepared for high temperatures and the increased risk of heat-related illnesses while recreating.

Heat strokes, heat exhaustion, heat cramps, sunburns and heat rash are all examples of heat-related illnesses.

Heat-related illnesses are caused by your body's inability to cool down properly. The body normally cools itself by sweating, but sometimes sweating just isn't enough. When this happens, the body's temperature rises rapidly and may damage the brain or other vital organs. Heat-related illnesses are serious and can lead to death if not treated quickly.

Several factors affect the body's ability to cool itself during extremely hot weather:

  • When the humidity is high, sweat will not evaporate as quickly, preventing the body from releasing heat quickly.
  • Participating in strenous physical activities, such as hiking or biking, in hot weather
  • Other factors that put you at higher risk of experiencing heat-related illness are age (infants, young children, people over 65), obesity, heart disease, poor circulation, fever, mental illness, dehydration, sunburn, and prescription drug and alcohol use.
  • Learn about heat-related illnesses. Familiarize yourself with the different types of heat-related illnesses, their causes, signs, and symptoms, and how to prevent them.

  • Become familiar with the park’s environment and weather conditions. Visit the park’s website or call the park to find out more about the environment and expected weather conditions during your visit. Learn more about the severe weather hazards that you might encounter.

  • Pick the right activity for you. Look at the “Plan Your Visit” section of the park’s website to pick an activity that is right for you and your group. Consider how daily temperatures will impact what time you should start your activity (early morning and late afternoon tend to be cooler) and how long you should be out in the park. Use the NPS Trip Planning Guide to help you get ready for your adventure.

  • Check the weather forecast and park alerts. Check the weather conditions and stop by the visitor center for information on heat alerts and high temperatures expected during your visit. If extreme heat is forecasted, schedule your activity for a cooler part of the day or plan to go out another day.


Water filling station at Grand Canyon
Michael Quinn, NPS

  • Plan for your water needs. Check that there are drinking water sources available at the park and along your trip route. Find out if there are potable refilling stations or natural water sources, which will require purification, along the trail if you plan to hike. If there are none, you will need to bring enough water with you for your trip.
  • Protect your skin. Wear sunscreen and have a hat, sunglasses, and extra water to help combat the high temperatures and prevent damage from UV light. Always carry the Ten Essentials with you.

  • Pick the right clothes. Wear lightweight, light-colored, loose-fitting clothes. Dark colors can absorb heat from the sun and increase your body temperature.

  • Exercise early in the day or later in the evening. If possible, schedule your activity before 10am or after 4pm to avoid the worst heat of the day. Check the park website for tips on when to go and how to avoid the hottest temperatures.

  • Do not leave children or pets in a parked vehicle. The temperature in a car can rise almost 20 degrees Fahrenheit in 10 minutes! Leaving a window cracked or open is not enough to stop the quick rise in temperatures. Children, who are left unattended, are at the greatest risk of heat illness that could lead to death.

  • Drink water often. Stay hydrated and drink before you feel thirsty. The amount of water you need may increase if you are exercising. Plan to bring extra water, just in case you need it. Sports beverages can help replace salt and minerals that you lose in sweat.

  • Rest often, and in the shade, if available. Soak yourself with water. On days with extreme heat, plan extra time to allow yourself to rest and cool off frequently during your activity. If water is available, consider completely soaking yourself to keep cool.
  • Follow “No swimming” and “No wading” signs. Many parks have rivers or lakes that might look like an inviting place to cool down, but in reality, are very dangerous. Many of these water bodies are very deceptive: the shoreline may have slippery rocks, and there may be strong currents and cold water temperatures that could lead to injury or death. Follow park rules and regulations on swimming or wading.
  • Take time to acclimate to high altitudes. You body loses more fluids at high altitudes, increasing your risk of dehydration and heat-related illnesses. Allow several days to acclimate to high altitudes before starting any strenuous exercise, like hiking or biking.

  • Stop what you are doing.
  • Move them into a cool, shaded area.
  • Call 9-1-1 or find a ranger for help.

  • While waiting for emergency responders, provide the person with drinking water.

  • Try to cool the person down by splashing or soaking them with water, if available, and fanning them vigorously.

NPS Trip Planning Guide PDF
NPS Trip Planning Guide

Don't let the heat keep you from exploring the park. Be a weather-ready explorer and check out the NPS Trip Planning Guide. Learn more about your Health & Safety in national parks.