10 Hot-Weather Running Tips to Stay Safe When Temperatures Rise

There are two types of runners: Those who love nothing more than to push through a hot, sweaty run and those who don’t. But no matter where you fall, running in the heat requires more than extra motivation.

Hot weather changes the way your body responds to exercise. As temperatures rise, your heart works harder, your pace may slow down, and your risk of heat-related ailments increases. The key is knowing how to adjust to the weather before you head out the door.

From slowing your speed and timing your runs wisely to hydrating properly and recognizing early warning signs of heat-related illness, here’s what every runner needs to know to stay safe and make the most of hot-weather miles.

1. Slow Down

A good rule of thumb to follow is for every 5-degree rise in temperature above 60 degrees Fahrenheit, your pace can slow by as much as 20 to 30 seconds per mile. So don’t fight it—just slow down.

2. Hydrate, Hydrate, Hydrate!

Top off your fluid stores with 16 ounces of sports drink an hour before you head out. Then, toss down five to eight ounces of sports drink about every 20 minutes while working out. Sports drinks beat water because they contain electrolytes, which increase your water-absorption rate, replace the electrolytes you lose in sweat, and taste good, making it easy to drink more.

3. Avoid Running in the Middle of the Day

Even in the worst heat wave, the temperatures are pretty cool at dawn. Get your run done then, and you’ll feel good about it all day. Can’t fit in a morning run? Wait until evening, when the sun’s rays aren’t as strong—just don’t do it so late that it keeps you from getting to sleep.

If you must run in the middle of the day, try to avoid long or higher-intensity workouts. Pick routes with some shade during the hottest part of the day. Also, start your workout slower than your normal pace.

4. Seek Grass and Shade

It’s always hotter in cities than in surrounding areas because asphalt and concrete retain heat. If you must run in an urban or even a suburban area, look for shade—any park or tree-lined stretch of road will do—and again, try to get your run done in the early morning or late evening.

5. Check the Breeze

If possible, start your run going with the wind so you return with a headwind. Running into the wind has a cooling effect, and you’ll need that more in the second half of a run than right in the beginning.

6. Dress Light

Wear apparel that’s light in color, lightweight, and has vents or mesh. Microfiber polyesters and cotton blends are good fabric choices. Also, be sure to wear a hat, shades, and sunscreen with an SPF of 30 or higher.

7. Learn the Side Effects of Meds

Antihistamines and antidepressants can have a dehydrating effect. Using them just before a run can make you have to pee, compounding your risk of dehydration.

8. Think Twice About Drinking Alcohol

Although it’s tempting to crack open a cold beer after your run, consider drinking water first to rehydrate and know that consuming too much alcohol can affect your recovery.

9. Be Patient

Give yourself eight to 14 days to acclimatize to hot weather, gradually increasing the length and intensity of your training through the first two weeks of warmer temps. In that time, your body will learn to regulate its core body temperature more efficiently so your heart rate decreases to a normal level.

10. If All Else Fails—Hit the Pool

Substitute one weekly outdoor walk or run with a pool-running session of the same duration. If you’re new to pool running, use a flotation device and simply move your legs as if you were running on land, with a slightly exaggerated forward lean and vigorous arm pump.

1. Heat Cramps

Cause: Dehydration leads to an electrolyte imbalance
Symptoms: Severe abdominal or large-muscle cramps
Treatment: Restore salt balance with foods or drinks that contain sodium
Prevention: Don’t run hard in the heat till acclimatized, and stay well hydrated with sports drink

2. Heat Fainting

Cause: Often brought on by a sudden stop that interrupts blood flow from the legs to the brain
Symptoms: Fainting
Treatment: After the fall, elevate legs and pelvis to help restore blood flow to the brain
Prevention: Cool down gradually after a workout with at least five minutes of easy jogging and walking

3. Heat Exhaustion

Cause: Dehydration leads to an electrolyte imbalance
Symptoms: Core body temperature of 102 to 104 degrees Fahrenheit, headache, fatigue, profuse sweating, nausea, clammy skin
Treatment: Rest and apply a cold pack on head/neck; also restore salt balance with foods and drinks with sodium
Prevention: Don’t run hard in the heat till acclimatized, and stay well hydrated with sports drink

4. Hyponatremia

Cause: Excessive water intake dilutes blood-sodium levels; usually occurs after running for four or more hours
Symptoms: Headache, disorientation, muscle twitching
Treatment: Emergency medical treatment is necessary; hydration in any form can be fatal
Prevention: When running, don’t drink more than about 32 ounces per hour; choose sports drink over water

5. Heatstroke

Cause: Extreme exertion and dehydration impair your body’s ability to maintain an optimal temperature
Symptoms: Core body temp of 104 degrees Fahrenheit or more, headache, nausea, vomiting, rapid pulse, disorientation
Treatment: Emergency medical treatment is necessary for immediate ice-water immersion and IV fluids
Prevention: Don’t run hard in the heat until acclimatized, and stay well hydrated with sports drink

Blisters, chafing, and sunburn can strike anytime, but they’re more common in hot weather. Here’s how to treat these problems and to prevent them from occurring before they sideline you.

1. Black Toenails

Cause: Lots of downhill running and too-small shoes can bring these on, as both cause your toes to slam into the front of your shoe.

Prevention: Wear properly fitted shoes and trim your nails regularly. Once you have a black toenail, there’s not much you can do to fix it. It’ll usually heal on its own within a few months. If it’s really painful, see a podiatrist, who may drain the fluid from under the nail.

2. Blisters

Cause: These are caused by friction, excessive moisture (sweaty feet, wet weather), or shoes that are too small, too big, or tied too tight. Buying properly fitted shoes is crucial, especially for summer running. Because your feet can expand a half size over the course of a day, shop in the late afternoon or evening.

Prevention: Putting Vaseline, sports lube, and/or bandages over blister-prone spots may also help. Ignore blisters smaller than 5 mm (the size of a pencil eraser), since they’re usually not painful. But pop the big ones. With a sterile needle, prick the side of the blister and drain it. Don’t remove the top of the blister; instead, cover it with an antibiotic ointment and moleskin or a bandage.

3. Chafing

Cause: Skin-to-skin and skin-to-clothing rubbing can cause a red, raw rash that can bleed, sting, and make you yelp during your postrun shower. Moisture and salt on the body make it worse. Underarms, inner thighs, along the bra line (women), and nipples (men) are vulnerable spots.

Prevention: To help prevent it, wear moisture-wicking, seamless, tagless gear. Fit is important—a baggy shirt has excess material that can cause irritation and a too-snug sports bra can dig into skin. Apply Vaseline, sports lube, Band-Aids, or NipGuards before you run. To treat chafing, wash the area with soap and water, apply an antibacterial ointment, and cover with a bandage.

4. Muscle Cramps

Cause: The best way to prevent these is to be well trained, because fatigue seems to be the main reason for cramping in races and hard workouts. Plyometric training (bounding, hopping) may lower your risk as well, and so may keeping well hydrated with a salty drink.

Prevention: If a cramp hits, stretch immediately. If your calf cramps, for instance, stop running, straighten out your leg, pull back on your toe, and hold the stretch for several seconds. You may need to continue this for several minutes. Then massage the muscle to help ease the pain and get you ready to run again.

5. Sunburn

Cause: Excessive exposure to sunlight without proper protection.

Prevention: To lower your risk, avoid the sun between 10 a.m. and 4 p.m., wear a hat, run in the shade, and wear sunscreen. Because sunscreen can’t withstand prolonged exercise, stash some in your pocket or circle back to your car so you can reapply every hour. You can also wear apparel that blocks UV rays. If you get sunburned, taking anti-inflammatory medication and applying aloe vera a few times per day will take the edge off the pain.

Finally, be aware of the heat index, which calculates the effect on your body of both the heat and the humidity. The heat index chart, from the National Weather Service, lets you know whether or not it’s safe to simply be outside, let alone run.

Forget about running outside when the heat index is high. Instead, hop on the treadmill or get some cross-training or strength work done—indoors.

Jennifer Van Allen

Former Special Projects Editor

Jennifer Van Allen was a former special projects editor for Runner’s World, where she managed the brand’s training programs and authored multiple books on running and race training, including The Runner's World's Big Book of Marathon and Half-Marathon Training. She is an RRCA- and USATF-certified run coach.