Climate averages 1991–2020
Chelmsford weather
in September.
A mild, moderately wet month: the 4th warmest and the joint 3rd driest of the year.
Long-term climate patterns, not a forecast for a particular trip.
September is a mild month in Chelmsford: daytime highs average 18.3°C and nights cool to about 11.8°C. By daytime temperature it is the 4th warmest of the 12 months.
Expect about 46 mm of rain on roughly 9 days, which makes September a moderately wet month (the joint 3rd driest of the 12 months). Daylight, from sunrise to sunset, lasts about 12 h 43 min on an average September day.
The nearest other city in this atlas is Basildon (19 km away). In September its highs average 18.2°C, about as warm as Chelmsford, with 45 mm of rain.
Among the 143 cities listed in the United Kingdom, Chelmsford ranks joint 17th of 143 for the warmest September highs and 10th of 143 for the driest September (rainfall, lowest first). The mean September high of those 143 cities is 17.3°C; Chelmsford is 1.0°C warmer than that mean.
From September to October, average highs fall by 3.9°C to 14.4°C, and monthly rainfall rises from 46 mm to 55 mm.
The annual picture
September in context
Monthly rainfall
Average total · mmAverages from hourly ERA5 reanalysis data. Actual weather varies from year to year. How these numbers are calculated
Every month, side by side
Chelmsford climate table
| Month | Average highHigh / low | Average low | Rainfall mm/month | Rain days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | 7.2°C2.7°C | 2.7°C | 50 | 10.7 | 8.48 h |
| February | 7.6°C2.5°C | 2.5°C | 41 | 9.1 | 9.910 h |
| March | 9.9°C3.8°C | 3.8°C | 39 | 10.0 | 11.812 h |
| April | 12.7°C5.6°C | 5.6°C | 46 | 10.8 | 13.814 h |
| May | 15.8°C8.6°C | 8.6°C | 51 | 9.8 | 15.616 h |
| June | 18.8°C11.6°C | 11.6°C | 53 | 9.9 | 16.617 h |
| July | 21.2°C13.8°C | 13.8°C | 53 | 10.8 | 16.216 h |
| August | 21.1°C13.9°C | 13.9°C | 59 | 9.9 | 14.615 h |
| September, selected | 18.3°C11.8°C | 11.8°C | 46 | 8.8 | 12.713 h |
| October | 14.4°C9.0°C | 9.0°C | 55 | 10.5 | 10.711 h |
| November | 10.2°C5.5°C | 5.5°C | 55 | 10.4 | 8.99 h |
| December | 7.6°C3.3°C | 3.3°C | 54 | 10.5 | 7.98 h |
Rainfall is the average of the 30 separate monthly totals. A rain day is a local calendar day with at least 1 mm of precipitation. Daylight is the calculated sunrise-to-sunset length, not measured sunshine.
Compare places
September in nearby cities
- Basildon in SeptemberUnited Kingdom · 19 kmHigh 18.2°C · Low 12.1°C · 45 mm rain
- Harlow in SeptemberUnited Kingdom · 25 kmHigh 18.3°C · Low 11.0°C · 48 mm rain
- Southend-on-Sea in SeptemberUnited Kingdom · 28 kmHigh 18.1°C · Low 12.5°C · 56 mm rain
- Dagenham in SeptemberUnited Kingdom · 29 kmHigh 18.5°C · Low 11.7°C · 45 mm rain
- Grays in SeptemberUnited Kingdom · 31 kmHigh 18.5°C · Low 11.8°C · 45 mm rain
- Ilford in SeptemberUnited Kingdom · 34 kmHigh 18.5°C · Low 11.6°C · 45 mm rain
- Colchester in SeptemberUnited Kingdom · 34 kmHigh 18.1°C · Low 12.3°C · 52 mm rain
- Barking in SeptemberUnited Kingdom · 35 kmHigh 18.6°C · Low 11.5°C · 45 mm rain
Read the numbers correctly
Climate, not a promise.
These patterns help compare months. They cannot tell you the weather on a specific day of your trip.
Sources, method and limitsHow these numbers are made (what the highs, lows and rain days mean, the sources and the model cell used for Chelmsford) is explained once on the Chelmsford year overview and on the Sources, method and limits page.