As someone who loves running, I’ve run in just about every weather condition you can imagine. Sunshine, rain, snow, wind, you name it – I’ve run through it.
Yet nothing prepares you quite like running in humidity. High humidity, combined with heat, can transform an easy jog into a grueling endurance test.
Here’s what you need to know before you head out in humid weather.
Why running in humidity is not the same as simply running in the heat
It’s important to note that running in humidity is not the same as running in heat alone. Heat can certainly make running harder, but when you add high humidity to the mix, it’s an entirely different ball game.
When the humidity is high, the air is saturated with water, which slows down the rate at which sweat evaporates from your skin.
Sweat evaporation is crucial because it helps regulate your body temperature and keep you cool.
Therefore, humidity makes hot weather feel even hotter – a phenomenon measured by the weather heat index. The heat index takes both temperature and relative humidity into account and provides an approximation of how the temperature feels to the human body. It is a useful tool for runners to gauge the ‘feels like’ temperature.
Once humidity levels climb above 60%, you will likely start to notice the effects on your body when you run.
The effect of running in humid weather on your body
Furthermore, the high heat and humidity can lead to higher dehydration levels, as your body will produce more sweat in an attempt to cool down.
This increased sweating, unfortunately, does not equate to more cooling, as the high humidity prevents the sweat from evaporating effectively.
The risks of running in high humidity
When you run in high humidity, several very serious risks can materialize. Heat exhaustion is one of them and presents symptoms like heavy sweating, rapid pulse, and dizziness.
In severe cases, heat stroke – a life-threatening condition characterized by a very high body temperature, rapid and strong pulse, and possibly unconsciousness – can occur.
Muscle cramps, often resulting from dehydration and loss of electrolytes, are another common ailment for runners in humid weather.
It’s widely understood that high humidity combined with high heat during exercise increases the risk of both heat exhaustion and heat stroke significantly.
Understanding these risks can help you make running in heat and humidity safer, and as always you should not only understand the risks yourself and exercise common sense when deciding if it’s safe for you to run outdoors, but also consider consulting your doctor before attempting to run in these conditions, especially if you’re new to running, are on medications or have other medical history that may make you more susceptible to these heat-related illnesses.
Acclimating to hot and humid climates and conditions
Despite these challenges, many runners still venture out for their summer running sessions. After all, the benefits of running far outweigh the discomfort – or at least, they usually do!
Like with getting your body used to running in other challenging conditions, such as running at altitude, acclimating to hot and humid conditions is possible and can help make running in high heat and humidity more bearable.
Acclimation usually involves a gradual process where you start with short, slow runs in the heat and humidity, gradually increasing your distance and speed over one to two weeks.
Listen to your body during this period. If you feel harder to breathe or show signs of heat exhaustion, slow down or stop running.
16 tips for running in humidity
Whether you’re a seasoned marathoner or a beginner hitting the pavement for the first time, running in humidity can be a challenging ordeal. However, with the right strategies and precautions, you can still have a safe and productive run.
These are my top tips for running in humidity:
1. Run early or late in the day
Consider adjusting your running schedule to avoid the peak heat and humidity, which usually occur in the afternoon.
Instead, opt for an early morning or late evening run when the temperature is cooler and humidity levels are typically lower.
An additional benefit of running at these times is the chance to catch a glorious sunrise or sunset, turning your workout into an inspirational experience.
2. Run slower and adjust your expectations
In humid conditions, your heart rate can be significantly higher at the same pace compared to running in cooler weather. This is your body’s response to the increased need for cooling. It’s perfectly normal and you should expect it.
Therefore, don’t be hard on yourself if you can’t maintain your usual pace. Adjust your expectations, slow down, and remember that you’re working just as hard, if not harder, than in cooler conditions.
3. Plan shorter routes or choose shaded areas
When the humidity is high, a long run can become a much harder task. Consider planning a shorter route to prevent overheating.
Also, try to choose a path with plenty of shade. Running under trees or near bodies of water can offer a respite from the heat and humidity.
4. Hydrate, hydrate, hydrate!
This tip cannot be overemphasized. Staying well-hydrated is crucial when you’re running in hot and humid weather.
Drink plenty of water before you head out, and if your run lasts more than 30 minutes, take a water bottle or hydration pack with you, and consider taking salt tablets or running gels with added salts to help you replenish lost electrolytes and reduce your chances of experiencing leg muscle cramps, especially if you expect to be running for over an hour.
After your run, replenish the fluids you’ve lost by drinking more water.
5. Dress appropriately
Wearing lightweight, breathable, and moisture-wicking clothing can make a significant difference in comfort when running in humidity. Opt for synthetic fabrics specifically designed for running and avoid cotton, which tends to retain moisture and can cause chafing.
A running hat or visor can protect your face from the sun, while a buff or bandana soaked in cold water can help keep your neck cool.
6. Apply sunscreen
Protecting your skin from the sun’s harmful rays is always essential when running outdoors, and even more so when you’re sweating excessively due to the heat and humidity.
Look for a waterproof or sweat-resistant sunscreen to ensure it stays put during your run.
7. Take breaks
Listen to your body and take breaks when needed. There’s no shame in slowing down, stopping to hydrate, or walking for a bit.
If you start feeling dizzy, lightheaded, or overly fatigued, stop running, find a shaded area, and hydrate.
8. Eat light before your run
Eating a heavy meal before running in high heat and humidity can make you feel sluggish and might even lead to stomach discomfort.
Opt for a light snack, such as a banana or a granola bar, about 1-2 hours before your run.
9. Gradually acclimate to the conditions
If you’re not accustomed to running in humid conditions, allow your body time to adjust. Start with shorter, slower runs and gradually increase your distance and pace over a few weeks.
As mentioned earlier in this post, this gradual exposure to the temperature and humidity will help your body adapt.
10. Use the treadmill on extreme days
Despite our love for running in the open air, there are days when the weather simply isn’t conducive to a healthy outdoor run.
When the heat index is dangerously high, consider swapping the pavement for a treadmill or an alternative, preferably indoor, form of cross-training suitable for runners. Indoor running allows you to control your environment and avoid the risks associated with extreme heat and humidity.
11. Stay cool post-run
After you finish your run, try to cool down your body temperature quickly. This can be done by taking a cool shower (or an ice bath), drinking cold fluids, or staying in an air-conditioned environment.
Lowering your body temperature after a hot run aids recovery and reduces the risk of heat-related illnesses.
12. Monitor your heart rate
If you have a fitness tracker or running watch, use it to keep an eye on your heart rate. Humidity can cause your heart rate to increase because your heart is working harder to help cool your body.
If your heart rate is significantly higher than normal, slow down or take a break.
13. Know the signs of heat-related illnesses
Awareness is key when it comes to heat-related illnesses, such as two of the most dangerous: heat exhaustion and heat stroke, which are both serious and potentially fatal conditions.
Familiarize yourself with the signs of these conditions, which can include nausea, dizziness, rapid heartbeat, headache, confusion, fainting, and in extreme cases, unconsciousness. To learn more, consult an appropriate source, such as this guidance on heat illnesses from the CDC.
If you notice any of these signs, stop running immediately, find a cool place, hydrate, and seek medical attention if symptoms persist. On that note, it may also be advisable to discuss your plans for running in hot and humid weather with your doctor, before you start training in these conditions.
14. Use a humidity and dew point chart
Use a chart (like this one by the National Weather Service) to understand how running will feel under different levels of humidity and dew point. It can be a useful tool to prepare for your run and adjust your pace and distance accordingly.
15. Partner up
Running with a buddy in hot and humid conditions can not only be motivational but also safer.
You can keep an eye on each other for signs of heat exhaustion, and it’s more likely that one of you will have a cell phone in case of emergency.
16. Change your mindset
Last but certainly not least, try to embrace the challenge. Running in humidity will feel harder, but it’s also a test of your mental strength – which makes it great training if you run, or are training your body and mind to run, long endurance races such as half marathons, marathons and 50k+ ultramarathons!
Use it as an opportunity to build your resilience, and remember that your performance in these conditions does not define your running ability.
In summary, running in humidity doesn’t have to be an insurmountable hurdle, if you remember to listen to your body, adjust your pace, stay cool, hydrate, and know when to take it indoors.