I live in Tennessee. According to the statistics, the year-round humidity level in Memphis is 67%. To put that in perspective, anything above 55% is considered high humidity. A humidity level of 70% is regarded as extreme. So, really, what I’m saying is it’s wet out here!
Combine that with Southern temperatures, and things get steamy.
Running in humid weather, especially here in the South, presents unique challenges due to heat stress, increased sweat rate, and stunted cooling efficiency. To maintain peak performance, runners must adjust their training, hydration, and recovery strategies. Whether you’re a beginner runner living in a muggy climate or an experienced runner visiting one for a race, knowing how to navigate adverse conditions is all part of the sport!
The Key Physiological Challenges of Running in High Humidity
Reduced Evaporative Cooling: High humidity limits sweat evaporation, making it harder to regulate core temperature. Sweat tends to stay on the skin because the air is already saturated with moisture.
Increased Cardiovascular Strain: Due to the difficulty in regulating core temperatures in humid conditions, more blood is directed to the skin for cooling. That means there’s less blood flow to muscles.
Higher Perceived Exertion: The body feels like it’s working harder, even at slower paces.
If you’re not used to running in these adverse conditions, you might feel discouraged. It can feel like running in molasses! Not only can humidity impact performance, but it can pose some unique risks. Here’s how to stay on top and stay safe!
How to Maintain Peak Performance in Humid Conditions
Strategy #1 – Heat Acclimation
Think of running in humid conditions as equivalent to altitude training. You need time to acclimate to the extra demands these conditions put on the body. Gradually train in the heat over 7–14 days, starting with short sessions and increasing duration and intensity.
Expect an elevated heart rate and RPE (rate of perceived exertion) initially, but this will improve over time. You may even want to try walking first before you ramp up to a full run.
Even easy effort runs in the heat help your body adapt (sweating earlier, improved plasma volume, better thermoregulation). Don’t worry so much about time and intensity in the beginning.
Strategy #2 – Emphasize Hydration
Humidity is deceptive. You might think you’d dehydrate faster in the desert, but here’s what happens. Your body doesn’t understand the difference between dew points. It just knows it needs to cool down. Because that sweat isn’t evaporating (and thus, isn’t cooling you down efficiently), you wind up sweating more. And that means dehydrating more.
Bring plenty of water and/or sports drinks to stay hydrated. Include sodium, magnesium, and potassium—not just water—to avoid hyponatremia.
Strategy #3 – Adjust Pacing and Expectations
Run by effort, not pace. Use heart rate or perceived exertion rather than your speed or mile times. You will be slower in high heat and humidity. It’s just how it goes. This is normal and necessary to prevent overheating.
To alleviate the stress of these conditions, consider doing your speed work during the cooler parts of the day, such as early morning or dusk. I recommend wearing bug spray in the evenings
Strategy #4 – Cooling Techniques
Wear light-colored, moisture-wicking clothing, especially those made from tech fabrics. Use ice packs pre-run or ice vests during warm-ups for races. Pour cold water on your head, neck, and wrists during runs. You’re going to get wet anyway, so it might as well be cold, too!
Post-run cool-downs with fans or ice baths accelerate recovery and lower core temperature faster. You may even want to try gadgets like neck fans or cooling towels.
Strategy #5 – Fueling
Carbohydrate intake becomes more important in hot and humid weather due to increased energy demands. Use easily digestible fuels, such as gels, chews, and drinks, and test them during long runs.
Avoid caffeine and alcohol beforehand—they contribute to quicker dehydration.
Strategy #7 – Listen to Warning Signs
Most importantly, STOP running if you experience symptoms of heat exhaustion (dizziness, nausea, chills, confusion, lack of sweating, etc.) It might be harder to notice these symptoms depending on the humidity levels.
As a safety precaution, run with a buddy, or let someone know your route and anticipated finish time if you're heading out in extreme heat.
Why not just AVOID running in humid weather?
Consider heat acclimation as a performance enhancer: Once adapted, racing in cooler weather can lead to noticeable performance boosts. Again, it’s a lot like altitude training.
That said, if you need a break from it (I understand, trust me!), cross-train indoors (cycling, elliptical) on high-humidity days to maintain fitness without heat exposure.
What are your best strategies for better running performance on hot, muggy days? Share in the comments.