Fetch historical wind and air density for your ride. Wind is applied per data point using the instantaneous GPS bearing, so headwind and tailwind sections are correctly handled even on out-and-back courses. Air density via Open-Meteo (free, no key needed).

Wind direction is where wind comes from (meteorological convention). Wind is applied point-by-point using the GPS bearing between each consecutive trackpoint — correctly accounting for direction changes on out-and-back and winding courses.