September is one of the warmer months of the year in Truro, with average highs near 19.9°C and lows around 10.4°C (mean 15.2°C). It is about average for rainfall, averaging 85 mm of rainfall and 80% relative humidity across the period.
September is one of the warmer months of the year in Truro. Across 45 years of records, the warmest September in Truro was 1999 — when the month averaged 18.6°C — while the coldest was 1986 at 12.1°C. Typical September days reach 19.9°C with nights near 10.4°C. The long-term trend is warming, about 0.4°C per decade.
September is about average for rainfall in Truro, averaging 85 mm of rainfall. The wettest September on record was 2012 with 224 mm, while the driest was 1985 at 15 mm.
Relative humidity in Truro during September averages 80%. The most humid September was 2013 at 86%, and the least humid was 1995 at 69%.
September receives about 3.8 kWh/m²/day of solar energy in Truro. The sunniest Septembers were 2003, 2009 and 2025, among others at 4.3 kWh/m²/day, and the cloudiest was 1996 at 3.2.
Average wind speed in Truro during September is 0.6 m/s. The windiest Septembers were 2019, 2020 and 2022, among others at 0.7 m/s, while the calmest were 2003, 2011 and 2023, among others at 0.5 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 14.3°C | 15.2°C | 14.7°C | 15.6°C | 16.4°C | +2.1°C |
| Avg High | 19.0°C | 20.2°C | 19.5°C | 20.2°C | 21.2°C | +2.2°C |
| Avg Low | 9.5°C | 10.3°C | 10.0°C | 10.9°C | 11.6°C | +2.1°C |
| Avg Rain | 75 mm | 85 mm | 84 mm | 101 mm | 75 mm | +0 mm |
September temperatures in Truro have risen by about 1.8°C between 1981–1985 and 2021–2025.
September has ranged from a record low of 1.1°C (2000) to a record high of 31.2°C (2010).
Rainfall in September is about average for rainfall, averaging 85 mm, with a wettest year of 224 mm.
One of the best times to visit Truro
September is one of the best times to visit Truro. Expect days averaging 19.9°C and nights around 10.4°C (mean 15.2°C) — warmer than Truro's yearly average — with higher rainfall (85 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 | 22.7°C | 17.0°C | 11.4°C | 28.6°C | 6.9°C | 29 mm | 73% | 0.6 m/s | 4.3 |
| 2024 | 20.4°C | 15.8°C | 11.1°C | 27.2°C | 7.9°C | 56 mm | 84% | 0.6 m/s | 3.8 |
| 2023 | 21.9°C | 17.3°C | 12.7°C | 29.5°C | 5.8°C | 56 mm | 83% | 0.5 m/s | 3.6 |
| 2022 | 20.8°C | 16.2°C | 11.6°C | 27.7°C | 7.2°C | 113 mm | 78% | 0.7 m/s | 3.9 |
| 2021 | 20.9°C | 16.4°C | 12.0°C | 25.9°C | 6.8°C | 123 mm | 85% | 0.6 m/s | 3.5 |
| 2020 | 20.7°C | 15.8°C | 10.8°C | 27.7°C | 4.0°C | 77 mm | 78% | 0.7 m/s | 3.9 |
| 2019 | 18.5°C | 14.0°C | 9.5°C | 24.8°C | 3.2°C | 100 mm | 83% | 0.7 m/s | 3.9 |
| 2018 | 21.0°C | 15.7°C | 10.4°C | 29.3°C | 3.8°C | 122 mm | 78% | 0.6 m/s | 4.1 |
| 2017 | 21.3°C | 16.7°C | 12.1°C | 27.0°C | 5.5°C | 90 mm | 84% | 0.6 m/s | 3.6 |
| 2016 | 20.1°C | 15.7°C | 11.3°C | 27.9°C | 5.1°C | 69 mm | 83% | 0.6 m/s | 3.7 |
| 2015 | 21.1°C | 16.2°C | 11.2°C | 26.6°C | 4.3°C | 59 mm | 84% | 0.6 m/s | 4 |
| 2014 | 20.5°C | 15.2°C | 9.9°C | 28.0°C | 3.6°C | 78 mm | 78% | 0.6 m/s | 4.1 |
| 2013 | 19.2°C | 14.7°C | 10.3°C | 26.0°C | 5.6°C | 116 mm | 86% | 0.6 m/s | 3.3 |
| 2012 🌧️ | 20.1°C | 15.8°C | 11.5°C | 26.4°C | 5.1°C | 224 mm | 85% | 0.6 m/s | 3.6 |
| 2011 | 20.6°C | 15.8°C | 11.1°C | 25.5°C | 5.7°C | 57 mm | 83% | 0.5 m/s | 4.2 |
| 2010 | 19.8°C | 15.7°C | 11.6°C | 31.2°C | 5.1°C | 98 mm | 85% | 0.6 m/s | 3.3 |
| 2009 | 17.6°C | 13.0°C | 8.3°C | 23.7°C | 3.5°C | 59 mm | 84% | 0.6 m/s | 4.3 |
| 2008 | 18.0°C | 14.0°C | 10.0°C | 23.5°C | 3.4°C | 121 mm | 86% | 0.6 m/s | 3.6 |
| 2007 | 18.8°C | 14.3°C | 9.8°C | 26.9°C | 5.2°C | 62 mm | 82% | 0.6 m/s | 4.2 |
| 2006 | 18.9°C | 14.5°C | 10.1°C | 23.0°C | 5.7°C | 36 mm | 85% | 0.6 m/s | 3.8 |
| 2005 | 20.5°C | 15.9°C | 11.3°C | 25.7°C | 6.0°C | 115 mm | 81% | 0.6 m/s | 3.8 |
| 2004 | 18.8°C | 14.0°C | 9.2°C | 24.9°C | 4.7°C | 74 mm | 78% | 0.7 m/s | 3.9 |
| 2003 | 21.3°C | 16.2°C | 11.0°C | 27.0°C | 5.2°C | 72 mm | 81% | 0.5 m/s | 4.3 |
| 2002 | 20.6°C | 15.5°C | 10.5°C | 30.5°C | 2.9°C | 139 mm | 81% | 0.6 m/s | 3.7 |
| 2001 | 21.0°C | 15.7°C | 10.4°C | 29.6°C | 5.9°C | 75 mm | 77% | 0.6 m/s | 4.3 |
| 2000 | 19.0°C | 14.2°C | 9.3°C | 27.0°C | 1.1°C | 81 mm | 80% | 0.6 m/s | 3.7 |
| 1999 🔥 | 23.9°C | 18.6°C | 13.2°C | 30.6°C | 6.2°C | 104 mm | 79% | 0.5 m/s | 4 |
| 1998 | 19.2°C | 14.7°C | 10.2°C | 23.7°C | 5.3°C | 94 mm | 82% | 0.5 m/s | 3.4 |
| 1997 | 20.1°C | 15.3°C | 10.5°C | 25.3°C | 2.8°C | 78 mm | 79% | 0.6 m/s | 3.3 |
| 1996 | 18.2°C | 14.3°C | 10.5°C | 27.3°C | 3.8°C | 194 mm | 84% | 0.6 m/s | 3.2 |
| 1995 | 20.2°C | 14.4°C | 8.6°C | 26.1°C | 2.9°C | 33 mm | 69% | 0.6 m/s | 3.9 |
| 1994 | 19.3°C | 14.5°C | 9.7°C | 25.2°C | 5.0°C | 59 mm | 77% | 0.6 m/s | 3.7 |
| 1993 | 21.3°C | 15.8°C | 10.3°C | 28.9°C | 4.5°C | 38 mm | 74% | 0.6 m/s | 3.4 |
| 1992 | 21.0°C | 15.8°C | 10.5°C | 27.1°C | 4.5°C | 47 mm | 76% | 0.5 m/s | 4 |
| 1991 | 18.2°C | 14.0°C | 9.7°C | 26.3°C | 3.1°C | 125 mm | 83% | 0.6 m/s | 3.3 |
| 1990 | 20.2°C | 14.8°C | 9.4°C | 28.0°C | 5.3°C | 76 mm | 77% | 0.6 m/s | 3.7 |
| 1989 | 21.2°C | 15.3°C | 9.5°C | 30.0°C | 1.5°C | 51 mm | 73% | 0.6 m/s | 3.9 |
| 1988 | 18.1°C | 13.4°C | 8.6°C | 24.1°C | 5.0°C | 51 mm | 77% | 0.7 m/s | 3.8 |
| 1987 | 18.5°C | 14.3°C | 10.1°C | 25.5°C | 3.0°C | 131 mm | 80% | 0.6 m/s | 3.7 |
| 1986 ❄️ | 16.9°C | 12.1°C | 7.3°C | 25.4°C | 4.2°C | 105 mm | 79% | 0.6 m/s | 4 |
| 1985 | 19.9°C | 15.0°C | 10.1°C | 26.2°C | 6.3°C | 15 mm | 78% | 0.6 m/s | 4 |
| 1984 | 18.1°C | 13.4°C | 8.8°C | 23.3°C | 2.8°C | 87 mm | 81% | 0.6 m/s | 4.1 |
| 1983 | 20.6°C | 15.7°C | 10.8°C | 28.1°C | 5.2°C | 50 mm | 80% | 0.6 m/s | — |
| 1982 | 19.2°C | 14.6°C | 10.0°C | 25.0°C | 6.3°C | 105 mm | 85% | 0.5 m/s | — |
| 1981 | 18.9°C | 14.7°C | 10.5°C | 25.2°C | 4.4°C | 83 mm | 80% | 0.7 m/s | — |
Actual recorded September data for each year, 1981–2025 — sourced from NASA POWER.
The average high in September is around 19.9°C with lows near 10.4°C (mean 15.2°C), based on 45 years of NASA POWER data.
September averages 85 mm of rainfall in Truro, about average for rainfall. The wettest on record was 224 mm in 2012.
The hottest September reached 31.2°C in 2010. The coldest dipped to 1.1°C in 2000.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average September temperatures have risen by about 1.8°C. Daytime highs moved from 19.3°C to 21.3°C and overnight lows from 10°C to 11.8°C over the same span.
September is one of the warmer months of the year in Truro and about average for rainfall, so plan for around 19.9°C daytime highs and 10.4°C at night.
Not quite — September is the 10th coolest month in Truro, averaging 15.2°C.
For September in Truro, pack light layers you can adjust through the day, with typical highs of 19.9°C and lows of 10.4°C. Bring an umbrella or light rain jacket too.
Relative humidity in September averages 80% — quite humid.
Average wind speed in September is 0.6 m/s. The windiest September on record averaged 0.7 m/s (1981).
The wettest September on record was 2012 with 224 mm. On average, September sees 85 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 Truro 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.
