The summer season makes us want to spend more time outdoors. Who wants to be on a treadmill inside when you could be outside enjoying the beautiful weather? When it’s excessively hot, though, it can be unpleasant and even dangerous to exercise outside. To keep up your workout routine during sweltering temperatures, you need to be aware and be prepared.

First, make sure you check the temperature and humidity. If it’s too hot and humid for sweat to evaporate, then your body can’t cool down, which could lead to heat stroke. The chart below from the National Weather Service makes it easy to figure out the heat index and know whether you should exercise outside (Note that this chart is for shady locations; if you are in direct sunlight, the heat index can go up by as much as 15℉). And remember, it’s not about how tough you are, so don’t put yourself at risk unnecessarily.

Courtesy of the National Weather Service

If you’ve determined it’s safe to exercise outside, try these tips:

Time of Day Matters – exercise in the early morning or late evening when the sun is not so intense and it’s cooler.

Hydrate – A couple hours before you work out, drink a couple cups of water, then drink about 8 ounces every 10-20 minutes during your workout. After, drink enough water to replace the fluid you lost through sweat.

Dress for the Weather – Wear lightweight, loose fitting, breathable clothing. Avoid dark colors and thick fabrics.

Try Shorter Workouts – Consider two shorter workouts, one in the morning and another at night.

Find the Cool Spot – If possible, find the cooler location in your area to exercise, such as a shady park.

Know the Signs of Heat Disorders and Heat Stroke – If you feel any of the following, stop exercising and find a place to cool down: fatigue, weakness, headache, dizziness, nausea, vomiting, or heat cramps.