September is one of the warmer months of the year in Chester, with average highs near 19.1°C and lows around 11.2°C (mean 15.2°C). It is about average for rainfall, averaging 89 mm of rainfall and 85% relative humidity across the period.
September is one of the warmer months of the year in Chester. Across 45 years of records, the warmest September in Chester was 1999 — when the month averaged 18.4°C — while the coldest was 1986 at 12.5°C. Typical September days reach 19.1°C with nights near 11.2°C. The long-term trend is warming, about 0.4°C per decade.
September is about average for rainfall in Chester, averaging 89 mm of rainfall. The wettest September on record was 1996 with 254 mm, while the driest was 1985 at 16 mm.
Relative humidity in Chester during September averages 85%. The most humid September was 2021 at 89%, and the least humid was 1981 at 81%.
September receives about 4 kWh/m²/day of solar energy in Chester. The sunniest September was 2007 at 4.6 kWh/m²/day, and the cloudiest was 1996 at 3.3.
Average wind speed in Chester during September is 1.2 m/s. The windiest Septembers were 1981 and 1996 at 1.4 m/s, while the calmest was 2003 at 0.9 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 14.5°C | 15.0°C | 15.0°C | 15.7°C | 16.1°C | +1.6°C |
| Avg High | 18.5°C | 18.9°C | 19.0°C | 19.6°C | 19.9°C | +1.4°C |
| Avg Low | 10.4°C | 11.0°C | 10.9°C | 11.9°C | 12.3°C | +1.9°C |
| Avg Rain | 68 mm | 98 mm | 73 mm | 105 mm | 105 mm | +37 mm |
September temperatures in Chester have risen by about 1.3°C between 1981–1985 and 2021–2025.
September has ranged from a record low of 3.1°C (2000) to a record high of 29.7°C (2010).
Rainfall in September is about average for rainfall, averaging 89 mm, with a wettest year of 254 mm.
One of the best times to visit Chester
September is one of the best times to visit Chester. Expect days averaging 19.1°C and nights around 11.2°C (mean 15.2°C) — warmer than Chester's yearly average — with higher rainfall (89 mm), so conditions are generally comfortable for sightseeing and outdoor plans.
| Year | Avg High | Avg Temp | Avg Low | Hottest Day | Coldest Day | Rainfall | Humidity | Wind | Solar |
|---|---|---|---|---|---|---|---|---|---|
| 2025 | 20.5°C | 16.4°C | 12.2°C | 24.7°C | 6.6°C | 46 mm | 84% | 1.2 m/s | 4.5 |
| 2024 | 19.7°C | 15.6°C | 11.6°C | 24.6°C | 8.6°C | 99 mm | 87% | 1.2 m/s | 4.1 |
| 2023 | 20.7°C | 17.0°C | 13.4°C | 25.8°C | 7.8°C | 106 mm | 88% | 1.2 m/s | 3.7 |
| 2022 | 19.6°C | 16.0°C | 12.3°C | 24.3°C | 7.0°C | 129 mm | 85% | 1.3 m/s | 4 |
| 2021 | 19.9°C | 16.5°C | 13.1°C | 23.2°C | 9.2°C | 152 mm | 89% | 1.2 m/s | 3.7 |
| 2020 | 19.2°C | 15.3°C | 11.3°C | 24.7°C | 4.2°C | 98 mm | 86% | 1.2 m/s | 4 |
| 2019 | 18.6°C | 14.5°C | 10.4°C | 22.9°C | 5.7°C | 95 mm | 84% | 1.3 m/s | 4.3 |
| 2018 | 20.2°C | 16.1°C | 12.1°C | 26.4°C | 4.1°C | 124 mm | 84% | 1.3 m/s | 4.3 |
| 2017 | 20.4°C | 16.8°C | 13.2°C | 24.8°C | 6.8°C | 111 mm | 88% | 1.1 m/s | 3.7 |
| 2016 | 19.5°C | 15.8°C | 12.1°C | 25.3°C | 5.8°C | 85 mm | 86% | 1.2 m/s | 4.1 |
| 2015 | 21.0°C | 16.9°C | 12.8°C | 25.9°C | 5.5°C | 89 mm | 86% | 1.1 m/s | 4.3 |
| 2014 | 19.2°C | 15.1°C | 11.0°C | 26.0°C | 4.0°C | 71 mm | 84% | 1.2 m/s | 4.3 |
| 2013 | 18.7°C | 14.8°C | 10.9°C | 24.6°C | 6.1°C | 128 mm | 88% | 1.2 m/s | 3.7 |
| 2012 | 19.1°C | 15.6°C | 12.0°C | 23.1°C | 6.2°C | 212 mm | 88% | 1.2 m/s | 3.8 |
| 2011 | 19.6°C | 15.8°C | 12.0°C | 23.4°C | 6.4°C | 54 mm | 87% | 1.1 m/s | 4.2 |
| 2010 | 19.6°C | 16.0°C | 12.4°C | 29.7°C | 7.7°C | 79 mm | 86% | 1.2 m/s | 3.7 |
| 2009 | 17.8°C | 13.6°C | 9.4°C | 22.8°C | 5.9°C | 56 mm | 86% | 1.2 m/s | 4.3 |
| 2008 | 18.1°C | 14.6°C | 11.0°C | 22.1°C | 4.7°C | 92 mm | 87% | 1.2 m/s | 3.8 |
| 2007 | 19.0°C | 15.0°C | 11.0°C | 25.0°C | 5.9°C | 58 mm | 83% | 1.2 m/s | 4.6 |
| 2006 | 19.1°C | 15.0°C | 11.0°C | 23.0°C | 6.5°C | 38 mm | 86% | 1.2 m/s | 4 |
| 2005 | 19.9°C | 15.9°C | 11.9°C | 24.7°C | 6.8°C | 86 mm | 86% | 1.2 m/s | 4.2 |
| 2004 | 17.9°C | 13.8°C | 9.7°C | 21.4°C | 4.3°C | 77 mm | 85% | 1.2 m/s | 4.2 |
| 2003 | 20.2°C | 16.1°C | 12.0°C | 24.5°C | 6.9°C | 95 mm | 85% | 0.9 m/s | 4.4 |
| 2002 | 20.1°C | 15.9°C | 11.7°C | 28.8°C | 4.1°C | 85 mm | 83% | 1.1 m/s | 4 |
| 2001 | 19.7°C | 15.5°C | 11.3°C | 25.1°C | 6.7°C | 51 mm | 84% | 1.1 m/s | 4.4 |
| 2000 | 18.4°C | 14.3°C | 10.3°C | 25.5°C | 3.1°C | 89 mm | 85% | 1.2 m/s | 4 |
| 1999 🔥 | 22.7°C | 18.4°C | 14.1°C | 29.0°C | 8.3°C | 68 mm | 82% | 1.1 m/s | 4.1 |
| 1998 | 18.5°C | 14.8°C | 11.1°C | 22.2°C | 6.5°C | 86 mm | 86% | 1.2 m/s | 3.6 |
| 1997 | 18.5°C | 14.8°C | 11.1°C | 21.7°C | 5.0°C | 53 mm | 86% | 1.2 m/s | 3.6 |
| 1996 🌧️ | 18.0°C | 14.8°C | 11.5°C | 24.5°C | 6.4°C | 254 mm | 88% | 1.4 m/s | 3.3 |
| 1995 | 17.8°C | 13.6°C | 9.3°C | 22.9°C | 4.2°C | 43 mm | 82% | 1.2 m/s | 4 |
| 1994 | 17.8°C | 14.1°C | 10.3°C | 22.0°C | 6.0°C | 94 mm | 86% | 1.2 m/s | 3.9 |
| 1993 | 19.2°C | 15.3°C | 11.5°C | 24.0°C | 5.2°C | 92 mm | 85% | 1.2 m/s | 3.6 |
| 1992 | 19.0°C | 14.8°C | 10.6°C | 23.6°C | 4.1°C | 120 mm | 85% | 1.1 m/s | 4 |
| 1991 | 18.2°C | 14.3°C | 10.3°C | 24.8°C | 3.6°C | 96 mm | 84% | 1.2 m/s | 3.7 |
| 1990 | 19.1°C | 14.8°C | 10.6°C | 23.4°C | 6.6°C | 78 mm | 83% | 1.2 m/s | 3.9 |
| 1989 | 19.6°C | 15.0°C | 10.4°C | 27.2°C | 3.3°C | 108 mm | 82% | 1.2 m/s | 4.4 |
| 1988 | 17.3°C | 13.3°C | 9.2°C | 22.0°C | 5.8°C | 56 mm | 82% | 1.2 m/s | 4.1 |
| 1987 | 18.2°C | 14.5°C | 10.8°C | 23.7°C | 4.1°C | 78 mm | 83% | 1.3 m/s | 3.9 |
| 1986 ❄️ | 16.8°C | 12.5°C | 8.3°C | 21.9°C | 4.2°C | 93 mm | 84% | 1.2 m/s | 4.3 |
| 1985 | 18.9°C | 14.8°C | 10.7°C | 24.0°C | 5.9°C | 16 mm | 84% | 1 m/s | 4.1 |
| 1984 | 17.8°C | 13.6°C | 9.5°C | 22.8°C | 4.1°C | 64 mm | 84% | 1.3 m/s | 4.5 |
| 1983 | 20.1°C | 16.1°C | 12.0°C | 25.4°C | 6.3°C | 29 mm | 83% | 1.2 m/s | — |
| 1982 | 19.0°C | 15.1°C | 11.1°C | 23.2°C | 6.9°C | 100 mm | 87% | 1 m/s | — |
| 1981 | 19.0°C | 15.2°C | 11.4°C | 24.3°C | 5.6°C | 65 mm | 81% | 1.4 m/s | — |
Actual recorded September data for each year, 1981–2025 — sourced from NASA POWER.
The average high in September is around 19.1°C with lows near 11.2°C (mean 15.2°C), based on 45 years of NASA POWER data.
September averages 89 mm of rainfall in Chester, about average for rainfall. The wettest on record was 254 mm in 1996.
The hottest September reached 29.7°C in 2010. The coldest dipped to 3.1°C in 2000.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average September temperatures have risen by about 1.3°C. Daytime highs moved from 19°C to 20.1°C and overnight lows from 10.9°C to 12.5°C over the same span.
September is one of the warmer months of the year in Chester and about average for rainfall, so plan for around 19.1°C daytime highs and 11.2°C at night.
Not quite — September is the 10th coolest month in Chester, averaging 15.2°C.
For September in Chester, pack light layers you can adjust through the day, with typical highs of 19.1°C and lows of 11.2°C. Bring an umbrella or light rain jacket too.
Relative humidity in September averages 85% — quite humid.
Average wind speed in September is 1.2 m/s. The windiest September on record averaged 1.4 m/s (1981).
The wettest September on record was 1996 with 254 mm. On average, September sees 89 mm.
All figures are derived from NASA POWER (Prediction Of Worldwide Energy Resources), based on MERRA-2 satellite reanalysis, covering 1981–2025.
Explore how the weather in Chester behaves each September, based on 45 years of NASA POWER climate data from 1981 to 2025. This page breaks down average temperatures, rainfall, humidity, wind and solar radiation for September specifically, along with year-by-year records and how the month has changed over the decades.
