Running in wind

Wind is the factor runners most often forget to check, yet it can swing a run more than a few degrees of temperature. A headwind forces you to push more air out of the way, raising the effort needed to hold a given pace; gusts also break your rhythm and can make footing unpredictable. Crucially, the math is asymmetric — a headwind costs you more time than the equivalent tailwind gives back, so an out-and-back route into the wind is a net loss.

Wind also amplifies the temperature you actually feel. In the cold it drives wind chill; in the heat a breeze can help evaporative cooling, but a hot, dry wind can also accelerate dehydration. RunWeather weighs sustained wind speed and direction rather than just the headline number, so the score reflects what the wind will really do to your effort.

To plan around it: run the first half into the wind so you finish with it at your back, choose sheltered routes on the gustiest days, and check the timeline — wind often eases in the early morning and picks up through the afternoon. Each city's page shows when the windy season arrives.