September in Chelmsford averages a daily high of 20.1°C with nights around 10°C. Expect roughly 9.9 wet days totalling 44.5mm. Comfortable conditions for being outdoors all day.
Across the year, the best time to visit Chelmsford is June–September.
Based on WRITTLE, UK (2.7km), 1995–2024. 29 years of September data.