Running in the heat is one of the biggest challenges recreational runners face, especially if you're training through summer for a fall race. With the right adjustments, you can keep your fitness, stay safe and even use summer training to your advantage.
1. Slow Down (And Accept It)
Heat raises your heart rate and makes every pace feel harder. A pace that feels easy at 60°F will feel hard at 85°F. That's physiology, not weakness.
Adjust your expectations. Many runners slow their easy pace by 30–90 seconds per mile when it's hot and humid, or run by effort and heart rate instead of pace. Use the Training Pace Calculator as a starting point, then go by feel.
2. Run Early or Late
The coolest parts of the day are around sunrise and after sunset. In hot climates like a Texas summer, a 6am run can be dramatically cooler than a late-morning one. That's the difference between a productive workout and a survival march.
3. Hydrate Before You Run
Start your run well hydrated. Drinking water in the hours before you run (for example, about 16–20 oz 1–2 hours before) is a common guideline. For longer runs in the heat, consider adding electrolytes. Our Hydration Calculator gives you a rough starting estimate.
4. Carry Water on Longer Runs
In the heat, don't count on finding fountains. For runs longer than about 45 minutes, carry your own water:
- Handheld bottle: cheapest and most flexible
- Hydration vest: best for long runs
- Hydration belt: a middle ground
5. Know the Heat Illness Warning Signs
This is the most important tip on the list. Heat illness can escalate quickly.
Stop running and get to shade if you notice:
- Dizziness, confusion or acting "off"
- Nausea or vomiting
- A headache that gets worse
- Chills, goosebumps, or hot skin that's no longer sweating
- A heart rate that won't come down
Cool down with water and shade. Confusion, collapse or very hot skin can mean heat stroke, which is a medical emergency, so call 911.
6. Wear the Right Gear
Clothing: light colors and moisture-wicking fabric. Technical shirts beat cotton in the heat.
Hat or visor: keeps direct sun off your head and face.
Sunscreen: SPF 30+ on exposed skin.
Sunglasses: reduce glare and eye strain on long, sunny runs.
7. Shorten or Split Your Runs
Summer training is about keeping your fitness safely, not hitting cool-weather numbers. In peak heat it's completely fine to:
- Cut long runs short
- Break one run into two shorter sessions
- Move a run indoors to the treadmill (see the treadmill pace chart)
8. Let Heat Acclimatization Work for You
Your body adapts to heat over roughly 10–14 days of regular exposure. After that, you start sweating earlier, your blood plasma volume rises, and the same pace feels easier. Build up gradually: start with shorter, easier runs in the heat.
That's one reason runners who train through a hot summer often feel great in cool fall races.
9. Electrolytes Matter as Much as Water
You lose sodium and other electrolytes in sweat. On long, hot runs, drinking large amounts of plain water without replacing sodium can lead to hyponatremia (low blood sodium), which is dangerous. For runs over about 75 minutes in the heat, use a sports drink or an electrolyte mix during and after. Common options include Nuun, Liquid I.V., Precision Hydration and Skratch Labs.
10. Recover Well After Hot Runs
- Rehydrate: drink fluids with some sodium soon after you finish.
- Refuel: carbs plus protein within about an hour.
- Cool down: a cool shower, cold towels on your neck, or air conditioning.
- Sleep: heat makes sleep worse, so make it a priority.
FAQ
How hot is too hot to run? There's no single number. The heat index (temperature plus humidity) matters more than the temperature alone. When the heat index is very high, many coaches recommend moving to the treadmill or taking a rest day, especially if you're not acclimatized.
Should I race in the heat? If race day is hot, adjust your goal. Slow your target pace, start conservatively and drink at every aid station.
Does running in the heat burn more calories? Slightly, but not enough to matter. Never skip fluids to "sweat more." That's dangerous.
What should I eat before a hot run? Something light and easy to digest 1–2 hours before, like a banana, toast with peanut butter or a small smoothie.
Planning a fall race? Use the Race Time Predictor to set a goal, then find one in the race calendar.