By Marnie Kunz, NASM-certified trainer, USATF- RRCA-certified run coach

Running in heat and humidity is more than a sweat-fest, it can also be dangerous. But with the right precautions, you can survive the heat and still get in your workouts. Whether you live in a place with humid summers like me (hello, Brooklyn), or in a climate that is hot year-round, these 20 tips for running in heat and humidity will help you stay safe and active. As a running coach, I've helped many runners navigate running in the heat, and these are my top strategies for running in high humidity and high temperatures.

Before I offer my coaching tips, I also want to go over some basic guidelines for temperatures and humidity so you can avoid dangerous heat.

When Is It Too Hot to Run?

Although we can take precautions when running in heat and humidity, there are times when it’s too hot to run outside. Running in extreme heat can raise your core body temperature too much and cause heat illnesses like heat cramps, heat exhaustion, and heat stroke.

Check the National Weather Service Heat Index Chart to see any warnings based on the temperature and humidity level in your area.

Avoid running outside if the heat is above 98.6 degrees and the humidity is above 70-80%, advises the Road Runners Club of America. If you feel dizzy, nauseous, confused, light-headed, delirious, or if you stop sweating, then it is time to get out of the heat immediately. Drink water and put wet, cool towels on your body to cool down. If you still do not feel better, seek medical help.

Tips for Running in Heat

1. Allow time to adjust to the heat.

If you live in a climate that changes from cold to hot, give yourself two weeks to adjust to running in the heat. During this time do easy base runs at a relaxed pace. Focus on your effort level more than your running times and speed. Keep your intensity low to moderate and avoid high-intensity workouts like fast interval repeats.

2. Check humidity.

Humidity can make a big difference in how hot you get while running. If humidity is high, it prevents sweat from evaporating on the skin, which can quickly lead to overheating of your brain and organs. When humidity is above 40%, it makes the heat feel more intense and impedes the body’s ability to cool itself.

When you check the weather, look at the heat index, which accounts for the temperature and humidity. If humidity is high and the temperature is high, consider working out inside. If you do run outdoors, go slow, stay in the shade and bring plenty of water with electrolytes.

3. Avoid intense workouts on hot days.

It is a myth that only beginning runners are affected by the heat. In fact, going faster generates more heat, so elite athletes are especially at risk of being affected by the heat. Avoid speed workouts and fast-paced runs on hot days. Do some relaxed pace base miles instead and save the speed workouts and long runs for cooler days or the treadmill.

4. Prehydrate.

Hydrate before your run by drinking 16 ounces (2 cups) of water two hours before your run. This is also a good time to have a meal or snack. And 15 minutes before your run, drink another 6 to 8 ounces (about a cup) of water. Check out our running nutrition tips from a dietitian for more guidelines on fueling your runs.

5. Hydrate on the run.

Bring hydration on your run. Everyone’s sweat rates vary, as does the amount of heat you are dealing with, so I recommend listening to your body and drinking when you’re thirsty. A good basic hydration guideline for running in the heat is to drink a minimum of 4 to 6 ounces every 20 minutes (4 ounces is half a cup).

Disclaimer: When you buy through our links, we may earn a commission - at no extra expense to you. We only do this for products we have tried or come highly recommended. Learn more.

6. Take electrolytes.

When we sweat, we lose essential minerals through sweat, including sodium, chloride, potassium, magnesium, and calcium. Sweating excessively can lead to dehydration. Drink plenty of fluids before, during, and after your runs.

Put an electrolyte tablet in your water or opt for a sports drink with electrolytes for hot weather running. If you go the sports drink route, look for low-sugar options. I love Nuun tablets and drop one in a water bottle for hot weather running. Check out my tips on supplements for runners for more details on what nutrients you lose through sweat and how to replenish them.

7. Wear moisture-wicking clothing.

Running clothes with moisture-wicking fabrics will help you stay dry and keep your body temperature more regulated when running in high temperatures. Look for lightweight, loose clothing made of synthetic moisture-wicking materials such as polyester and nylon.

8. Wear light colors.

Lighter colors absorb less heat and darker colors absorb heat so opt for lighter colors.

9. Protect against the sun.

Wear sunscreen, a hat, and sunglasses to shield against harmful UV rays. Check out our article on the best sunscreen for runners for tips on the best sweat-proof sunscreen options.

10. Avoid peak heat hours.

Avoid running at peak heat times, which are between 10 am to 2 pm. Run in the early morning or later in the evening to avoid the hottest times. I recommend running in the early mornings as much as possible because the heat often lingers for hours after sundown.

11. Stick to the shade.

If you have to run when it’s sunny, stay in shady areas. Running near water, by trees, and in shade from buildings helps diffuse some of the heat. Try to avoid blacktop and cement as much as possible as it holds more heat. Of course, if you’re running in a big city like me, avoiding concrete is not always possible, and sometimes running in the shade of buildings is the best you can do.

12. Adjust your training schedule.

We runners can get caught up in numbers and stats and stick to training plans no matter what, but sometimes Mother Nature has other plans. If your only option is running in heat and humidity, you will need to adjust your training program. This can mean cutting miles from long runs, rescheduling speed workouts, or doing shorter runs in general.

13. Adjust your route.

If you are running in the heat, look at your route and revise if needed. Sometimes you will need to cut your running route to be shorter, in a shadier place (a park instead of a track, for instance), or to go by a water stop. Do what you need to do to make sure you have the best chance of staying hydrated and cool on your run.

14. Run with someone.

Having a running buddy improves your safety while running in heat and humidity. If you or your running partner gets too hot, then you can stop and help each other to get out of the heat and cool down. Note, if your dog is your running buddy, you should not run with your dog in the heat. If the temperature (in degrees Fahrenheit) and the humidity percent totals 150 or more, do not bring your dog on the run. See our tips for running with your dog for more guidelines on running with your furry friend.

15. Share your location.

If you run alone, it’s a good idea to share your location, especially if you’re running in heat and humidity. Running apps such as Strava have the option to share your location with a trusted contact, or you can use a safety app like ROAD iD to share your location. Our running safety tips offer more ideas on how to improve your safety while on the run.

16. Be flexible.

Be willing to adjust your workout program for the heat. Many runners I coach get frustrated with their slower times during the summer months, but that is normal, given the heat. You will run slower than usual in the heat. For every 5°F rise in temperature above 60°F, your running pace will slow by as much as 20 to 30 seconds per mile, according to Runner’s World.

17. Check your meds and alcohol consumption.

Limit your alcohol intake during periods of high heat. Also, be aware of your medications and their possible effects on hydration. Alcohol, antihistamines, and antidepressants can have dehydrating effects. If possible, don’t consume dehydrating medications right before your run. Still take your prescription medications of course but talk with your doctor about any heat-related risks and how to mitigate them.

18. Consider your age.

Heat affects people more as they get older. Sweat glands become less efficient as we age. More than 80 percent of the estimated 12,000 people in the U.S. who die of heat-related causes annually are over age 60, according to Climate Central. If you’re at an increased risk of heat illness based on your age, talk with your doctor about when it’s too hot for you to exercise outside, and always err on the side of caution.

19. Know the signs of heat illness.

Signs of heat exhaustion and heat stroke include heavy sweating, cold, pale, and clammy skin, a fast, weak pulse, nausea, vomiting, muscle cramps, tiredness, weakness, dizziness, headaches, and fainting. If you experience any of these symptoms, move to a cool, dry place, drink water or a sports drink, and put cool, wet cloths on your body or take a cool bath.

The signs of heat stroke include the same symptoms of heat exhaustion but more intense, with a high body temperature (103°F or higher), confusion, and losing consciousness. Call 911 for immediate assistance if you or someone you’re with has a heat stroke.

20. Exercise indoors.

If you’re in a heat wave that won’t relent or you must exercise during peak heat hours, then do an indoor workout. Run on the treadmill, lift weights, go to the gym, or do a HIIT workout at home. The key is to be flexible and stay protected from the most intense heat and humidity.

Do you enjoy running in hot weather? Comment below with your best tips for running in heat and humidity.

Happy running to you, and stay safe!😊

Resources: CDC Warning Signs and Symptoms of Heat-Related Illness

Marnie Kunz is a NASM-certified personal trainer and USATF- and RRCA-certified running coach based in Brooklyn, NY. Marnie likes helping people get and stay active to enjoy a better quality of life. When she’s not doing fitness things, Marnie enjoys exploring with her dog, a mischievous rescue Akita.

20 Tips for Running in Heat and Humidity