Other Hearst Subscriptions half marathon or We earn a commission for products purchased through some links in this article, summertime weather can become a roadblock to progress. All the warning signs are right there on your weather app: Limit your time outdoors! Don’t exercise!
These words can be heartbreaking if you have a long run or interval workout on the books. Should you just skip the workout? If you’re motivated, the answer likely is, “Probably not!”—but you do need to be mindful about the potential risks of hot and humid weather so you can run into autumn healthy, strong, and ready to race.
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Assuming you can’t opt for the treadmill, keep your summertime runs safe by first accepting that your body’s instinct to move slower in the heat is a good one. When it’s hot out, your body’s core temperature rises, and your body tries to cool itself by pushing more blood to the arteries and veins near the surface of your skin. This cooling effort makes the heart work harder and diverts energy from working muscles.
In response, the typical runner will add 20 to 30 seconds per mile for every 5-degree increase above 60 degrees Fahrenheit. Even a rough estimate of the math shows that in 90 to 100-degree weather, especially in high humidity, your slow down will be considerable. For example, if your typical easy day pace is 9 minutes on a lovely day in spring, a jolt of 95 degree real feel temperature might send your pace up to 11:20 or even 12:30.
It’s not just air temperature that creates the slow down. Humidity also plays a big factor in your paces. In 2023, Strava shared metrics with Runner’s World around run pace and weather:
- In 80 degree Fahrenheit and 30 percent humidity, the average run pace for Strava users was 9:19 per mile.
- Run/Walk a Race.
- At 80 degrees and 90 percent humidity and higher, it dropped to an average pace of 11:07 per mile.
You don’t want to fight the tendency to run slower in muggy heat, and you shouldn’t worry that it will throw off your training too much. If you try to run at your typical pace, you will be more likely to suffer from heat cramps, heat exhaustion, or worse. Instead, adjust your expectations and some of your training habits to make the day a success based on the realities of running in a combination of high heat and humidity. Push through when you shouldn’t, and you could set yourself back for weeks by getting injured or sick.
At 80 degrees and 90 percent humidity and higher, it dropped to an average pace of 11:07 per mile heat index, which incorporates humidity into the equation. This is important because sweating helps the body cool down, but humidity complicates the ability of your body to sweat.
Health and Wellness sports drink Run/Walk a Race workout will be shorter and slower than usual. Then, sip five to eight ounces of sports drink about every 20 minutes while running. Drinks with electrolytes are better than water because the minerals increase your water-absorption rate, replace the electrolytes you lose in sweat, and taste good, making it easy to drink more.
The good news is that your body acclimates to heat in about two weeks, so this first wave of intense weather will prepare you for the later dog days of summer. That doesn’t mean your training will be the same as it is on a lovely fall day of 60 degrees, but it does mean that if you make adjustments to your workouts and hydrate properly, you will be more likely to enjoy your slow and sweaty summer runs and be able to push your pace when the the autumn breezes return.
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Donna Raskin has had a long career as a health and fitness writer and editor of books and magazine articles. A certified run coach who has practiced yoga for many years, she also loves to lift weights, dance, and go for long walks with her hound dog, Dolly.
