It probably goes without saying, but humidity also plays a factor when running in hotter weather. The higher the humidity, the more fluids you will lose by sweating. Shortening your distance and lowering your pace will help you out, and remember to keep yourself adequately hydrated. You’re going to be losing a lot more water from your system on days with high humidity levels. Prepare accordingly. You may even want to prepare in advance. So check out the week’s forecasted temperature and humidity levels to see what you’re up against that week. A little preparation and planning time can go a long way since there are elevated risks that come with running in extreme temperatures. For instance, you can plan ahead and schedule your long run for a day with lower humidity levels.