Weather: The Big Half
Historical weather data for race day in September. Use this to plan your race strategy, clothing, and hydration.
13°C
Temperature
Range: 9°C – 17°C
65%
Humidity
Moderate
40%
Rain Chance
Possible — check forecast
September
Typical race month
Usually on a Sunday
Conditions
Spring weather with mild temperatures and occasional rain. Runners should expect cool conditions but generally pleasant running weather typical of London in April.
What to Wear
Singlet or short sleeve
Ideal racing temperatures
Hat with brim
Keep rain out of your eyes
Anti-chafe cream
Wet conditions increase chafing risk
Hydration Strategy
Before the Race
Normal hydration. Drink to thirst in the 24 hours before. Avoid over-hydrating.
During the Race
Drink at aid stations every 3-4km. Alternate water and sports drink.
After the Race
Rehydrate within 30 minutes of finishing. A drink with electrolytes and some protein helps recovery.
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