September is one of the cooler months of the year in Thames, with average highs near 15.4°C and lows around 10.3°C (mean 12.9°C). It is about average for rainfall, averaging 94 mm of rainfall and 81% relative humidity across the period.
September is one of the cooler months of the year in Thames. Across 45 years of records, the warmest September in Thames was 2005 — when the month averaged 13.8°C — while the coldest was 1992 at 11°C. Typical September days reach 15.4°C with nights near 10.3°C. The long-term September temperature trend is broadly flat.
September is about average for rainfall in Thames, averaging 94 mm of rainfall. The wettest September on record was 2022 with 194 mm, while the driest was 1993 at 17 mm.
Relative humidity in Thames during September averages 81%. The most humid Septembers were 2016 and 2023 at 86%, and the least humid was 1993 at 76%.
September receives about 3.7 kWh/m²/day of solar energy in Thames. The sunniest Septembers were 1990, 2018 and 2020, among others at 4.1 kWh/m²/day, and the cloudiest were 2010 and 2016 at 3.2.
Average wind speed in Thames during September is 3.1 m/s. The windiest September was 1981 at 4 m/s, while the calmest were 2006, 2009 and 2022, among others at 2.5 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 12.8°C | 12.4°C | 13.2°C | 12.8°C | 13.2°C | +0.4°C |
| Avg High | 15.3°C | 15.0°C | 15.9°C | 15.2°C | 15.7°C | +0.4°C |
| Avg Low | 10.4°C | 9.8°C | 10.4°C | 10.3°C | 10.7°C | +0.3°C |
| Avg Rain | 84 mm | 92 mm | 69 mm | 107 mm | 131 mm | +48 mm |
September temperatures in Thames have risen by about 0.6°C between 1981–1985 and 2021–2025.
September has ranged from a record low of 4.4°C (1993) to a record high of 19.7°C (2001).
Rainfall in September is about average for rainfall, averaging 94 mm, with a wettest year of 194 mm.
A quieter season to visit Thames
If your dates are flexible, the more temperate months of February and January tend to be the most comfortable for visiting Thames. That said, September — with days averaging 15.4°C and nights around 10.3°C (mean 12.9°C) and higher rainfall (94 mm) — can still be rewarding for travellers who don't mind the cooler conditions, and often means fewer crowds.
| Year | Avg High | Avg Temp | Avg Low | Hottest Day | Coldest Day | Rainfall | Humidity | Wind | Solar |
|---|---|---|---|---|---|---|---|---|---|
| 2025 | 15.7°C | 13.4°C | 11.1°C | 18.7°C | 7.9°C | 124 mm | 82% | 3.5 m/s | 3.6 |
| 2024 | 15.8°C | 13.1°C | 10.3°C | 17.9°C | 6.1°C | 64 mm | 82% | 3.2 m/s | 4 |
| 2023 | 15.9°C | 13.6°C | 11.3°C | 19.2°C | 7.9°C | 186 mm | 86% | 3.3 m/s | 3.9 |
| 2022 🌧️ | 15.8°C | 13.4°C | 11.1°C | 18.3°C | 7.5°C | 194 mm | 80% | 2.5 m/s | 3.6 |
| 2021 | 15.3°C | 12.8°C | 10.4°C | 17.8°C | 8.1°C | 168 mm | 81% | 3.2 m/s | 3.7 |
| 2020 | 15.5°C | 12.7°C | 9.8°C | 18.2°C | 5.5°C | 53 mm | 80% | 3.3 m/s | 4.1 |
| 2019 | 15.6°C | 13.0°C | 10.5°C | 17.5°C | 8.2°C | 118 mm | 82% | 3.3 m/s | 3.9 |
| 2018 | 15.4°C | 12.7°C | 10.1°C | 19.3°C | 6.7°C | 35 mm | 81% | 2.8 m/s | 4.1 |
| 2017 | 15.4°C | 13.0°C | 10.6°C | 18.0°C | 7.7°C | 136 mm | 84% | 3.1 m/s | 3.7 |
| 2016 | 15.6°C | 13.3°C | 11.0°C | 17.2°C | 5.8°C | 158 mm | 86% | 2.9 m/s | 3.2 |
| 2015 | 14.6°C | 12.1°C | 9.5°C | 17.0°C | 6.7°C | 109 mm | 81% | 2.8 m/s | 4 |
| 2014 | 15.4°C | 13.0°C | 10.5°C | 17.1°C | 5.3°C | 142 mm | 85% | 3.1 m/s | 3.6 |
| 2013 | 15.3°C | 13.0°C | 10.7°C | 18.3°C | 5.7°C | 107 mm | 82% | 3.4 m/s | 3.6 |
| 2012 | 15.0°C | 12.8°C | 10.5°C | 18.5°C | 4.7°C | 98 mm | 79% | 3.5 m/s | 3.7 |
| 2011 | 14.7°C | 12.0°C | 9.3°C | 16.3°C | 6.5°C | 65 mm | 78% | 3 m/s | 4 |
| 2010 | 15.4°C | 13.0°C | 10.7°C | 18.1°C | 8.2°C | 100 mm | 83% | 3.7 m/s | 3.2 |
| 2009 | 16.3°C | 13.3°C | 10.4°C | 19.6°C | 4.6°C | 83 mm | 81% | 2.5 m/s | 3.8 |
| 2008 | 15.9°C | 13.1°C | 10.4°C | 18.4°C | 8.9°C | 34 mm | 81% | 2.8 m/s | 3.9 |
| 2007 | 15.7°C | 13.2°C | 10.6°C | 17.9°C | 7.8°C | 51 mm | 81% | 2.6 m/s | 3.7 |
| 2006 | 16.3°C | 13.4°C | 10.6°C | 19.1°C | 8.2°C | 56 mm | 83% | 2.5 m/s | 3.7 |
| 2005 🔥 | 16.4°C | 13.8°C | 11.3°C | 18.5°C | 6.9°C | 70 mm | 82% | 2.9 m/s | 3.7 |
| 2004 | 14.5°C | 11.9°C | 9.2°C | 16.6°C | 5.8°C | 73 mm | 80% | 3.4 m/s | 3.6 |
| 2003 | 15.8°C | 13.3°C | 10.8°C | 18.9°C | 7.5°C | 135 mm | 84% | 3.5 m/s | 3.4 |
| 2002 | 15.7°C | 12.9°C | 10.2°C | 17.6°C | 6.3°C | 73 mm | 80% | 3.2 m/s | 3.6 |
| 2001 | 16.1°C | 13.5°C | 10.8°C | 19.7°C | 8.9°C | 59 mm | 80% | 2.6 m/s | 3.7 |
| 2000 | 16.1°C | 13.1°C | 10.0°C | 18.2°C | 5.5°C | 56 mm | 79% | 3 m/s | 3.7 |
| 1999 | 16.4°C | 13.4°C | 10.4°C | 17.7°C | 5.4°C | 56 mm | 80% | 2.6 m/s | 4 |
| 1998 | 16.3°C | 13.5°C | 10.7°C | 18.3°C | 7.6°C | 47 mm | 80% | 3.1 m/s | 3.7 |
| 1997 | 14.3°C | 12.2°C | 10.1°C | 16.2°C | 7.1°C | 151 mm | 83% | 3.1 m/s | 3.6 |
| 1996 | 15.9°C | 13.4°C | 10.9°C | 17.2°C | 6.7°C | 121 mm | 84% | 2.9 m/s | 3.6 |
| 1995 | 15.3°C | 12.7°C | 10.0°C | 18.7°C | 5.8°C | 98 mm | 82% | 2.8 m/s | 3.7 |
| 1994 | 14.3°C | 11.8°C | 9.3°C | 16.2°C | 6.8°C | 140 mm | 81% | 3.8 m/s | 3.6 |
| 1993 | 14.0°C | 11.3°C | 8.6°C | 17.7°C | 4.4°C | 17 mm | 76% | 3.3 m/s | 3.8 |
| 1992 ❄️ | 13.6°C | 11.0°C | 8.5°C | 15.1°C | 4.6°C | 98 mm | 83% | 3.1 m/s | 3.8 |
| 1991 | 14.9°C | 12.7°C | 10.6°C | 17.3°C | 7.0°C | 104 mm | 83% | 3.1 m/s | 3.8 |
| 1990 | 14.5°C | 11.9°C | 9.2°C | 16.6°C | 6.3°C | 89 mm | 78% | 2.6 m/s | 4.1 |
| 1989 | 15.9°C | 13.6°C | 11.3°C | 18.2°C | 5.6°C | 87 mm | 82% | 2.9 m/s | 3.7 |
| 1988 | 15.7°C | 13.4°C | 11.0°C | 18.1°C | 5.7°C | 85 mm | 85% | 3.1 m/s | 3.4 |
| 1987 | 14.9°C | 12.6°C | 10.3°C | 18.3°C | 8.6°C | 124 mm | 82% | 3.7 m/s | 3.7 |
| 1986 | 15.0°C | 12.3°C | 9.7°C | 17.4°C | 6.8°C | 67 mm | 82% | 3.2 m/s | 3.8 |
| 1985 | 14.9°C | 12.8°C | 10.8°C | 18.2°C | 7.7°C | 90 mm | 80% | 3.8 m/s | 4.1 |
| 1984 | 15.2°C | 12.6°C | 10.0°C | 17.0°C | 6.9°C | 93 mm | 82% | 2.7 m/s | 3.9 |
| 1983 | 16.0°C | 13.2°C | 10.3°C | 18.0°C | 6.0°C | 75 mm | 81% | 3.3 m/s | — |
| 1982 | 15.5°C | 12.7°C | 9.9°C | 18.2°C | 5.6°C | 45 mm | 79% | 2.5 m/s | — |
| 1981 | 14.7°C | 12.4°C | 10.2°C | 17.9°C | 6.7°C | 85 mm | 81% | 4 m/s | — |
Actual recorded September data for each year, 1981–2025 — sourced from NASA POWER.
The average high in September is around 15.4°C with lows near 10.3°C (mean 12.9°C), based on 45 years of NASA POWER data.
September averages 94 mm of rainfall in Thames, about average for rainfall. The wettest on record was 194 mm in 2022.
The hottest September reached 19.7°C in 2001. The coldest dipped to 4.4°C in 1993.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average September temperatures have risen by about 0.6°C. Daytime highs moved from 15.3°C to 15.7°C and overnight lows from 10.2°C to 10.8°C over the same span.
September is one of the cooler months of the year in Thames and about average for rainfall, so plan for around 15.4°C daytime highs and 10.3°C at night.
Not quite — September is the 4th coolest month in Thames, averaging 12.9°C.
For September in Thames, pack light layers you can adjust through the day, with typical highs of 15.4°C and lows of 10.3°C. Bring an umbrella or light rain jacket too.
Relative humidity in September averages 81% — quite humid.
Average wind speed in September is 3.1 m/s. The windiest September on record averaged 4 m/s (1981).
The wettest September on record was 2022 with 194 mm. On average, September sees 94 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 Thames 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.
