Given the strenuous nature of marathon running, the weather can have positive or negative impacts on performance, comfort, and safety. This is especially true of humidity, wind, and temperature, as the body's thermoregulation system is an inefficient heat management system, wherein muscles that are working hard produce up to 11x more heat than muscles at rest. As such, the timing of marathon races (e.g. morning) and the scheduling of marathon races (e.g. predominantly spring and fall) is intentional.
This study explores the impacts of weather on marathon runners' performance and comfort, across seasons. The findings show marathon runners cannot run in regular running gear in winter or summer, as the temperatures may be too severe and thus, dangerous.
CITE: Spellman, G. (1996). Marathon running - an all-weather sport? Weather, 51(4) ,118-125.