Over the past 10 years, London Marathon runners have faced temperatures ranging from 6\u00b0C (43\u00b0F) on cooler years to 16\u00b0C (61\u00b0F) in warmer editions. The median temperature of 11\u00b0C (52\u00b0F) puts this race in the neutral category for running conditions.
Wind speeds average 15 km/h during race hours, with peak gusts reaching 25 km/h in challenging years. Humidity sits around 60%, and there is a 40% chance of rain on race day.
These conditions translate to an estimated pace impact of +2.6% compared to ideal running conditions. For a 4-hour marathoner, that means roughly 6 minutes slower than a perfect-weather day.