As the runner’s rule of thumb goes, you should always dress like it’s 20 degrees warmer than it is. That’s why you see racers in singlets and shorts when it’s 45 degrees out: Once your furnace gets going, winter turns to spring and spring turns to summer.
But what do you do when it’s already summer? When a heat wave sets records seemingly every month, and when the humidity rises along with the temperature, making the ambient air feel like an oppressive sweater? Well, for one, you reset your expectations. You’re going to be slower, and everything’s going to feel harder. And for two, you think a little more about your running clothes and gear—which means making sure you have enough water and are as comfortable as possible.
There’s no across-the-board truism for running in the heat, and acclimatization is a hell of a drug: Some folks don’t leave the house without enough water for an overnight camping trip, while some camels can happily lope along under the blazing sun for an hour without noticing. But with WIRED’s Bay Area environs slogging into their own odd August-to-October version of summer, it’s time to make sure you’re prepared, from superlightweight clothing to hydration packs. Anything to stay off the dreadmill, right?
Be sure to check out our spring running gear guide, fitness watch picks, and our favorite trail running shoes.