Summer running in the South is no joke. Humidity that feels like a wet blanket. Temps pushing 90 before 8am. Asphalt that radiates heat back up at you like an oven. If you try to run your normal pace in those conditions, your body will let you know about it fast.
The good news is that heat training doesn’t have to wreck you. It just requires a different approach.
Your Body Is Working Harder Than You Think
Here’s the thing most runners miss. When it’s hot, your heart rate climbs even when you’re running slowly. Your cardiovascular system is now doing two jobs at the same time. It has to deliver oxygen to your working muscles AND pump blood to the skin surface so your body can cool itself through sweat.
That’s a real extra load. Your heart doesn’t care that you’re only doing an easy 6-miler. If it’s 88 degrees and 80% humidity, your HR is going to be elevated above where it would be on a cool morning. That’s physiology, not weakness.
Fighting it is a mistake. Working with it is the smart play.
Pace Adjustment: The 10-Second Rule
A simple rule I use with athletes: for every 5 degrees above 60°F, slow your easy pace by about 10 seconds per mile. That sounds conservative. It is. And it’s right.
If you normally run easy runs at a 9:00/mile pace, you should expect to run 9:30 to 9:50 on a 90-degree morning just to stay in the same aerobic zone. Your effort level stays the same. Your pace drops. That’s not regression. That’s smart training.
Trying to hit your normal pace numbers in extreme heat means you’re working at a higher intensity than you planned, burning more glycogen, spending more recovery time, and raising your injury risk. None of that is worth it.
Run by effort. Let the numbers be what they are.
Heart Rate Zones in the Heat
If you train with a heart rate monitor, heat running gives you a real chance to use it well. Your target zones don’t change just because it’s summer. What changes is how much work it takes to stay in them.
For easy aerobic runs, you want to stay in Zone 2. In hot conditions, that means slowing down more than your brain wants you to. Most athletes resist this. They feel like they’re barely running. But they’re getting the same aerobic benefit they would in cooler conditions. The adaptation is happening even if the pace doesn’t look impressive on Strava.
If your HR is creeping into Zone 3 and 4 on what was supposed to be an easy run, slow down. Walk if you need to. This isn’t failure. It’s the right call.
Hydration Changes the Equation
You can’t outrun dehydration in the heat. Even mild dehydration of 2% body weight raises your heart rate and tanks performance. By the time you feel thirsty, you’re already behind.
Pre-hydrate before you head out. Don’t skip sodium. Electrolytes matter more in summer than any other time of year. And if you’re going longer than 45 minutes in serious heat, you need to be taking in fluids during the run.
Consider the timing of your runs too. Early morning or after sunset is not just more comfortable. It’s physiologically smarter. Midday summer running in the Carolinas is genuinely risky if you’re not experienced and prepared.
Acclimatization Is Real
Here’s the upside. Your body adapts to heat training over 10 to 14 days of consistent exposure. Plasma volume increases. You start sweating earlier and more efficiently. Your HR response to the same workload drops. You actually get better at running in heat.
But that adaptation doesn’t happen if you skip every hot run or stay on the treadmill all summer. You have to earn it.
The athletes I coach who stay consistent through the Carolina summers come out the other side with real fitness. When fall race season arrives and temperatures drop, those athletes feel like they have another gear. That gear was built in the heat.
The Bottom Line
Run slower. Monitor your HR. Hydrate aggressively. Stop trying to hit your winter pace splits in August.
Summer running is an investment. Do it right and you’ll race well when it counts. Do it wrong and you’ll spend September recovering instead of performing.
If you want help dialing in your summer training plan, we’d love to work with you. Reach out at iamwithoutlimits.com/coaching.
Do the work.
Tom Clifford CEO, Without Limits Endurance USATF Level 2 Coach | USA Triathlon Coach