Every summer, I watch runners underestimate just how much heat changes the game. The air gets thicker, the sweat rate doubles, and suddenly that same easy pace feels like you’re dragging a backpack full of bricks.
Heat doesn’t care if you’re fit, seasoned, or tough — it humbles everyone eventually. That’s why running smart in the heat isn’t just about comfort. It’s about protecting performance, recovery, and your long-term health.
Understanding the Real Risk
According to the American College of Emergency Physicians, roughly 400 deaths occur each year from heat-related illness — and plenty more athletes end up in the ER for something that started as “just a little dizziness.”
The problem is that heat sneaks up on you. It builds gradually as your body struggles to offload excess temperature through sweat and skin circulation. When the air is hot and humid, that process gets blocked, and your core temperature can rise faster than you realize.
Runners love to push through discomfort — it’s practically part of the sport. But in extreme heat, that mindset can turn dangerous fast.
Recognizing the Warning Signs
Your body sends signals long before things get critical, and learning to spot them early can save you a lot of trouble.
If you start feeling nauseous, lightheaded, unusually fatigued, or like your legs just don’t have power — that’s heat exhaustion trying to get your attention. Cramping, dizziness, and chills are also early signs that your system is overheating.
That’s your cue to stop. Move to a shaded or air-conditioned spot, sip fluids with electrolytes, and cool your skin with water, ice, or cold towels. Most runners bounce back quickly if they act early.
Heat stroke is more serious. It’s when your body loses its ability to regulate temperature altogether. Symptoms can include confusion, a rapid pulse, flushed skin, or even loss of consciousness. This is a medical emergency — call for help immediately, move the person to a cooler area, and apply ice or cold compresses while waiting for assistance.
Adjusting Your Training (Without Losing Progress)
When the forecast shows triple digits or an Excessive Heat Warning, that’s your sign to adapt, not to grind harder.
The best summer runners aren’t the ones who suffer through the worst conditions — they’re the ones who know when to pivot. That might mean moving your runs to dawn, taking advantage of shaded routes, or using looped paths where you can set up a self-serve aid station with fluids and cooling gear.
If you’re in the menopausal or masters category, pay even closer attention. Hormonal changes can affect thermoregulation and fluid balance, meaning your body may struggle to cool itself as efficiently. You might find your threshold for heat tolerance is lower than it used to be — and that’s normal. Adapt around it instead of fighting it.
Hydration starts before your run. Drink throughout the day, add electrolytes during long or high-sweat sessions, and continue rehydrating afterward. Water alone won’t replace what you lose through heavy sweating, so sodium and potassium matter.
And yes, sometimes the smartest move is heading inside. A treadmill session or a swim can deliver the same aerobic benefit without the added stress of overheating.
Rethinking Pace and Perception
One of the biggest mistakes runners make in the summer is expecting their cool-weather paces to hold steady in the heat. They won’t. And that’s not a reflection of fitness — it’s physics.
Your heart rate runs higher in the heat, even at easy paces. That means “easy” on paper will feel like work. Instead of chasing your usual numbers, run by effort. Let your breathing, heart rate, and perceived exertion guide the day.
Remember: heat is a stressor, just like speedwork. Stack too many stressors at once and your recovery will suffer. Adjusting pace isn’t backing off — it’s keeping your training productive.
Understanding Comfort Levels
Once you start noticing how the heat index affects your effort, you’ll get better at predicting what your body can handle. A humid 75° morning might feel harder than a dry 85° evening. Conditions in the low 60s might feel “sticky,” while anything above 70° with humidity can be downright brutal.
Every athlete’s comfort range is different. The trick is learning yours and training within it, not against it.
Running in the heat requires more than grit. It requires awareness, flexibility, and respect for what your body is trying to tell you.
The goal isn’t to out-tough the weather — it’s to outsmart it. When you hydrate intentionally, adjust expectations, and learn to recognize early signs of stress, summer running becomes an opportunity to build resilience instead of burnout.
If you want help structuring your training around heat adaptation, hydration strategies, and recovery, let’s chat about a personalized coaching plan that fits your climate and goals.