What to Wear Running in the Heat

Running in the heat asks for less clothing and more strategy. Wear a singlet or the lightest tee you own, short shorts, and light colors, all in fabric that wicks and dries quickly. A breathable cap or visor shades your face and lets heat escape, and sunglasses cut glare on bright days. The clothing job is purely heat loss, so loose and light beats anything tight, heavy, or dark. Beyond what you wear, plan to soak a cap or buff at fountains and to carry or stash fluids, because in real heat your gear is the small part and your strategy is the big part.

The serious heat mistakes are about pace and timing, not clothing. Holding your normal pace, running at midday, and skipping fluids are how a hot run becomes a medical problem. Your body diverts blood to the skin to cool itself, so the same effort costs more and your heart rate climbs. The fix is to slow down without guilt, run at the cool ends of the day, and drink ahead of thirst. Learn the warning signs of heat illness: dizziness, chills, a pounding heart at easy effort, or suddenly not sweating all mean stop and cool down immediately.

Humidity is what separates a hard hot run from a dangerous one. When the air is dry, sweat evaporates and cools you, so heat is manageable at an easy effort. When it is humid, that cooling fails, the feels-like soars above the air temperature, and your body cannot keep up. On humid days cut the distance or intensity, judge the run by effort rather than pace, and consider moving it indoors. Heat acclimatization takes one to two weeks of gradual exposure, so the first warm days of the year are the riskiest and deserve the most caution.