…because we run FASTER in the Fall! That’s from running coach Michael Melinoitis. Because when the weather’s cooler, with less humidity, running takes less effort and there’s less resistance in dry air. So even at the same heart rate, you’ll go faster. The best weather for a run? 45 to 55 degrees Fahrenheit… or 10 degrees Celsius. That’s why there are more marathons in the Fall.