Marathon Weather: What to Expect

Temperature and pace

Most runners perform best in cool conditions — roughly 4–12 °C at the start for many elites, with slightly warmer acceptable for mortals. Heat forces slower pacing and higher heart rate; cold is usually easier to dress for than heat is to escape.

Humidity and sweat

High humidity reduces evaporative cooling. A flat, cool-looking forecast can still feel oppressive in the tropics or during humid summers. Check humidity ranges on each marathon page, not just temperature.

Wind and exposure

Coastal and river courses can be windy with little shelter. Out-and-back layouts may give a tailwind early and a headwind when you are most tired. Course video and route descriptions often flag exposed kilometres.

Rain and gear

Light rain is manageable; cold rain is miserable without throwaway layers. Many races allow a discarded top at the start — plan one if the forecast is borderline. See our race day checklist for what to pack.

Using weather to choose a race

Compare typical race-month conditions across your shortlist. If you overheat easily, bias toward spring and autumn races and northern latitudes. Pair this guide with best time of year to run a marathon and the calendar to align timing with climate.