Running Through the Furnace: Training Smart in Summer Heat

There’s no way around it — summer running means heat and humidity. But while the sun won’t cut you any slack, advance planning can make the difference between powering through and flaming out.

Let’s talk tactics.

1. Hydration: It’s a Week‑Long Job

“Drink water” is obvious — but it’s not that simple. The day you run matters, but the days leading up matter more.

If you’re only chugging water an hour before your long run, you're playing catch-up. Hydration is cumulative — your fluid intake over the week impacts how well your body regulates temperature and recovers from heat stress. Think of it like sleep: you can’t recover a week’s worth of sleep in one night, and you can’t fix a week’s worth of poor hydration with one bottle of water.

Mild dehydration (just a 1–2% loss in body water) has been shown to impair energy, focus, and workout performance. This Time article does a nice job summarizing several scientific studies regarding the timing and method of hydration, and how those variables impact performance. In particular, the article highlights how drinking water without any food consumption doesn’t do much for you. Without food, fluid retention is much lower.

2. Electrolytes Matter (But So Does Your Diet)

On hot days or during long runs, you don’t just lose water — you lose sodium, potassium, and other key minerals. Adding electrolytes helps your body hold onto the fluids you drink and supports recovery. You don’t have to rely on Gatorade if you don’t like it; you can get what you need from coconut water, salty snacks, adding a pinch of salt to your evening meal, or lower-sugar hydration tablets like Nuun.

3. Carrying Water Doesn’t Require a Backpack

Not everyone loves hydration backpacks, especially for shorter runs. Consider handheld bottles, waist belts, or vests with front pockets. For even simpler solutions:

• Leave water at the start of a looped route every 2–4 miles

• Plan runs that pass by parks or water fountains

• Run out-from-and-back-to your car or home so you can easily refill

That way, you stay hydrated without hauling a tank that’s going to slosh around on your back.

3. Dress for the Job

If you’re a heavy sweater, you already know that a soaked shirt in 90-degree heat can feel like wearing a wool blanket. Light colors help, but sometimes, less is more. If you’re comfortable with it, and in a safe area to do so, you can go shirtless or rock a sports bra. You’ll find it’s a fairly common practice in July and August Evaporative cooling can make a world of difference. Give your body a better shot at shedding heat.

4. Find a Reason to Go

Let’s be honest: some days, the heat wins the mental game. One thing that helps me? A little bribery. When I plan a long run on a brutal day, I also plan a reward — an açaí bowl, an iced coffee, a trip to Tropical Smoothie, a New York-style BEC. It doesn’t change the forecast, but it gives me a reason to push out the door, and the treat also feels well-earned which is a nice little mental bonus.

5. Adjust Your Expectations

Even if you feel good, your body is working harder in the heat. Don’t obsess over pace — focus on the effort. What feels like marathon pace in July might actually be marathon effort, even if the watch disagrees. That’s okay.

From personal experience, I’ve found that once the temperatures drop in the fall, so does my “easy” pace — without changing anything else. The fitness is there, it’s just hidden under the weight of the heat. Be patient and trust that you’re building strength that will show up when the weather turns.

Heat training makes you stronger long-term — but only if you don’t burn yourself out trying to prove something to your GPS.