September is one of the warmer months of the year in St. Clements, with average highs near 18.4°C and lows around 9.2°C (mean 13.8°C). It is about average for rainfall, averaging 56 mm of rainfall and 71% relative humidity across the period.
September is one of the warmer months of the year in St. Clements. Across 45 years of records, the warmest September in St. Clements was 2024 — when the month averaged 18.6°C — while the coldest was 1985 at 10°C. Typical September days reach 18.4°C with nights near 9.2°C. The long-term trend is warming, about 0.7°C per decade.
September is about average for rainfall in St. Clements, averaging 56 mm of rainfall. The wettest September on record was 2019 with 122 mm, while the driest was 2001 at 16 mm.
Relative humidity in St. Clements during September averages 71%. The most humid September was 2004 at 79%, and the least humid was 2012 at 62%.
September receives about 3.5 kWh/m²/day of solar energy in St. Clements. The sunniest Septembers were 2009 and 2011 at 4.1 kWh/m²/day, and the cloudiest was 1985 at 3.
Average wind speed in St. Clements during September is 3.8 m/s. The windiest Septembers were 1983, 1985 and 1991 at 4.3 m/s, while the calmest were 1987 and 2001 at 3.2 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 12.5°C | 13.5°C | 14.1°C | 13.8°C | 16.1°C | +3.6°C |
| Avg High | 16.9°C | 18.2°C | 18.6°C | 18.3°C | 20.7°C | +3.8°C |
| Avg Low | 8.1°C | 8.8°C | 9.5°C | 9.2°C | 11.5°C | +3.4°C |
| Avg Rain | 56 mm | 46 mm | 65 mm | 66 mm | 38 mm | -19 mm |
September temperatures in St. Clements have risen by about 4.9°C between 1981–1985 and 2021–2025.
September has ranged from a record low of -3.5°C (2018) to a record high of 32.7°C (2023).
Rainfall in September is about average for rainfall, averaging 56 mm, with a wettest year of 122 mm.
One of the best times to visit St. Clements
September is one of the best times to visit St. Clements. Expect days averaging 18.4°C and nights around 9.2°C (mean 13.8°C) — warmer than St. Clements's yearly average — with moderate rainfall (56 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 | 21.7°C | 17.2°C | 12.8°C | 27.7°C | 5.4°C | 39 mm | 71% | 3.5 m/s | 3.4 |
| 2024 🔥 | 23.3°C | 18.6°C | 13.9°C | 28.4°C | 8.8°C | 35 mm | 70% | 3.9 m/s | 3.8 |
| 2023 | 21.8°C | 17.3°C | 12.9°C | 32.7°C | 7.1°C | 41 mm | 70% | 3.4 m/s | 3.6 |
| 2022 | 19.3°C | 14.8°C | 10.3°C | 29.3°C | 3.2°C | 33 mm | 71% | 3.9 m/s | 3.8 |
| 2021 | 20.8°C | 16.1°C | 11.4°C | 26.4°C | 7.4°C | 50 mm | 70% | 4 m/s | 3.8 |
| 2020 | 17.1°C | 12.3°C | 7.5°C | 25.4°C | 1.6°C | 29 mm | 70% | 4.1 m/s | 3.5 |
| 2019 🌧️ | 18.1°C | 14.0°C | 9.8°C | 27.0°C | 2.4°C | 122 mm | 77% | 3.6 m/s | 3.2 |
| 2018 | 15.9°C | 11.5°C | 7.1°C | 26.1°C | -3.5°C | 59 mm | 70% | 3.7 m/s | 3.3 |
| 2017 | 18.2°C | 14.0°C | 9.8°C | 27.2°C | 5.4°C | 92 mm | 74% | 4.1 m/s | 3.3 |
| 2016 | 19.3°C | 14.8°C | 10.3°C | 26.7°C | 4.4°C | 56 mm | 74% | 4 m/s | 3.4 |
| 2015 | 20.5°C | 15.8°C | 11.2°C | 29.3°C | 4.2°C | 67 mm | 72% | 3.9 m/s | 3.7 |
| 2014 | 17.8°C | 13.1°C | 8.4°C | 25.9°C | 3.7°C | 41 mm | 76% | 3.7 m/s | 3.3 |
| 2013 | 20.5°C | 15.7°C | 10.8°C | 29.6°C | 4.6°C | 61 mm | 70% | 3.7 m/s | 3.8 |
| 2012 | 18.1°C | 13.1°C | 8.2°C | 27.5°C | 0.8°C | 22 mm | 62% | 4.1 m/s | 3.4 |
| 2011 | 19.1°C | 14.2°C | 9.3°C | 28.9°C | 2.6°C | 41 mm | 69% | 4 m/s | 4.1 |
| 2010 | 15.3°C | 11.4°C | 7.4°C | 21.5°C | 3.2°C | 95 mm | 77% | 4.1 m/s | 3.5 |
| 2009 | 22.6°C | 17.7°C | 12.9°C | 26.8°C | 1.9°C | 50 mm | 76% | 3.6 m/s | 4.1 |
| 2008 | 17.5°C | 13.3°C | 9.1°C | 24.1°C | 4.0°C | 104 mm | 75% | 3.5 m/s | 3.5 |
| 2007 | 17.6°C | 13.1°C | 8.5°C | 27.2°C | 0.5°C | 62 mm | 73% | 3.9 m/s | 3.1 |
| 2006 | 18.7°C | 13.9°C | 9.0°C | 27.2°C | 3.2°C | 78 mm | 69% | 3.4 m/s | 3.8 |
| 2005 | 18.9°C | 14.4°C | 10.0°C | 25.9°C | 4.5°C | 41 mm | 74% | 3.6 m/s | 3.8 |
| 2004 | 19.2°C | 14.7°C | 10.3°C | 26.7°C | 5.2°C | 82 mm | 79% | 3.6 m/s | 3.2 |
| 2003 | 17.3°C | 13.2°C | 9.0°C | 28.9°C | -0.6°C | 83 mm | 75% | 4.1 m/s | 3.2 |
| 2002 | 19.1°C | 14.5°C | 9.9°C | 27.9°C | -0.7°C | 67 mm | 70% | 3.9 m/s | 3.5 |
| 2001 | 19.2°C | 14.2°C | 9.2°C | 27.2°C | 1.1°C | 16 mm | 68% | 3.2 m/s | 3.9 |
| 2000 | 16.3°C | 11.6°C | 7.0°C | 24.5°C | 0.4°C | 65 mm | 74% | 3.9 m/s | 3.2 |
| 1999 | 15.8°C | 11.5°C | 7.3°C | 23.0°C | 1.6°C | 58 mm | 73% | 3.9 m/s | 3.1 |
| 1998 | 20.0°C | 15.3°C | 10.7°C | 30.2°C | 4.7°C | 30 mm | 68% | 3.6 m/s | 3.8 |
| 1997 | 19.8°C | 15.1°C | 10.3°C | 26.4°C | 4.2°C | 25 mm | 67% | 4.2 m/s | 3.7 |
| 1996 | 19.0°C | 14.3°C | 9.5°C | 28.8°C | 1.7°C | 55 mm | 69% | 3.6 m/s | 3.4 |
| 1995 | 18.8°C | 13.7°C | 8.5°C | 27.9°C | 0.7°C | 23 mm | 64% | 3.5 m/s | 3.9 |
| 1994 | 21.1°C | 16.1°C | 11.2°C | 29.1°C | 4.3°C | 54 mm | 66% | 3.6 m/s | 3.8 |
| 1993 | 14.8°C | 10.4°C | 5.9°C | 19.3°C | 1.7°C | 26 mm | 73% | 4.1 m/s | 3.2 |
| 1992 | 16.4°C | 11.7°C | 7.0°C | 21.6°C | 0.6°C | 54 mm | 70% | 4.1 m/s | 3.2 |
| 1991 | 16.8°C | 12.4°C | 8.0°C | 27.5°C | 0.5°C | 99 mm | 68% | 4.3 m/s | 3.4 |
| 1990 | 19.3°C | 14.2°C | 9.1°C | 29.0°C | 2.7°C | 40 mm | 66% | 4 m/s | 3.6 |
| 1989 | 18.7°C | 13.6°C | 8.6°C | 27.1°C | 0.9°C | 18 mm | 65% | 3.9 m/s | 3.9 |
| 1988 | 17.1°C | 12.7°C | 8.2°C | 26.8°C | 3.9°C | 70 mm | 69% | 4.1 m/s | 3.2 |
| 1987 | 19.4°C | 14.8°C | 10.2°C | 27.2°C | 5.0°C | 29 mm | 69% | 3.2 m/s | 3.5 |
| 1986 | 16.1°C | 12.0°C | 7.8°C | 20.3°C | 3.6°C | 68 mm | 72% | 3.4 m/s | 3.2 |
| 1985 ❄️ | 13.9°C | 10.0°C | 6.0°C | 21.8°C | -1.2°C | 52 mm | 75% | 4.3 m/s | 3 |
| 1984 | 14.8°C | 10.6°C | 6.4°C | 24.3°C | -0.6°C | 77 mm | 69% | 3.7 m/s | 3.2 |
| 1983 | 17.8°C | 13.4°C | 9.0°C | 31.9°C | 0.7°C | 56 mm | 68% | 4.3 m/s | — |
| 1982 | 17.2°C | 12.7°C | 8.1°C | 29.1°C | 2.0°C | 50 mm | 70% | 4 m/s | — |
| 1981 | 17.5°C | 12.9°C | 8.4°C | 26.6°C | 0.9°C | 86 mm | 68% | 4 m/s | — |
Actual recorded September data for each year, 1981–2025 — sourced from NASA POWER.
The average high in September is around 18.4°C with lows near 9.2°C (mean 13.8°C), based on 45 years of NASA POWER data.
September averages 56 mm of rainfall in St. Clements, about average for rainfall. The wettest on record was 122 mm in 2019.
The hottest September reached 32.7°C in 2023. The coldest dipped to -3.5°C in 2018.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average September temperatures have risen by about 4.9°C. Daytime highs moved from 16.2°C to 21.4°C and overnight lows from 7.6°C to 12.3°C over the same span.
September is one of the warmer months of the year in St. Clements and about average for rainfall, so plan for around 18.4°C daytime highs and 9.2°C at night.
Not quite — September is the 9th coolest month in St. Clements, averaging 13.8°C.
For September in St. Clements, pack light layers you can adjust through the day, with typical highs of 18.4°C and lows of 9.2°C. Bring an umbrella or light rain jacket too.
Relative humidity in September averages 71% — moderately humid.
Average wind speed in September is 3.8 m/s. The windiest September on record averaged 4.3 m/s (1983).
The wettest September on record was 2019 with 122 mm. On average, September sees 56 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 St. Clements 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.
