Chelmsford Half Marathon
Race Day Weather
Comfortable temps, warming through the race, strong wind
Mild 53°F temps at gun time mean comfortable early miles without overheating risk. Temperatures rising to 64°F through the course will gradually increase perceived effort in the second half. Strong 23mph gusts could slow exposed stretches — tuck behind other runners when you can. Moderate humidity at 71% is worth noting for effort level, especially in later miles.
Pace Calculator
Get forecast alerts for Chelmsford Half Marathon
We'll text or email you when the forecast shifts — so you can adjust gear, pacing, and strategy. Max one per day.
Get your personalized Chelmsford Half Marathon race plan
True Effort pacing, weather-adjusted mile splits, fueling timeline with aid stations, packing checklist, carb tracker, spectator guide — all personalized to your goal and race-day conditions.
Race Info
The Chelmsford Half Marathon starts and finishes in Central Park, Chelmsford, on the same morning as the marathon. Runners share the marathon's opening route through West Park and past Writtle University toward Roxwell, then turn back for Central Park just past the six-mile mark, while the marathon continues on into the Essex countryside. The out-and-back course runs on quiet, undulating country lanes through the Writtle and Roxwell area.
