During the hottest weather of the year, it can be difficult to go for a run outside without issues like dehydration or lack of energy. While you can't control the day-to-day air temperatures or humidity, here's a short list of factors you can implement to make your summer runs more enjoyable.
Remember, hydration is key. It's important to make sure you're getting water before, during and after your run. To stay hydrated while running, you can try a special running belt or no-grip water bottle. You can also leave water along your route or plan for spots to refill. If you know you'll be out for a long time, consider bringing along an electrolyte drink to replenish yourself.
Keep your body temperature down. A common deterrence from running in summer is how hot your body can feel when outside. One rule of thumb to know is that your body temperature will feel a minimum of 20 degrees warmer than the air temperature. So, if the air is 90 degrees, your body will feel like 110 degrees. Likewise, if it's only 60 degrees, your body will feel like 80 degrees. It can actually be better to run in a long-sleeve shirt, as it blocks the sun from beating down on your bare skin. Choose moisture-wicking, loose-fitting clothing and avoid cotton.
Don't overdo your miles outdoors. It can be tempting to keep pushing your limits, but during extreme temperatures you'll need to be more mindful. Try to focus more on building distance instead of speed training during summer, as your body is already working harder than usual. If you have access to a treadmill or indoor area, take advantage of those resources on the very hottest days so as to not overwork yourself outdoors.
Choose your time wisely. Avoid the middle of the afternoon when deciding what time to go out running. This is the hottest point of the day and comes with more risk of heatstroke, dehydration or overexerting yourself. Ideally, run before sunrise or after sunset for the coolest temperatures. Always be sure to let someone know the route you will be running in case of emergency or you start feeling sick.
If you're interested in finding more information on running and how to stay safe, check out these trustworthy resources.
Runner's World
New York Road Runners
Brooks Running