September is one of the warmer months of the year in Truro, with average highs near 17.1°C and lows around 13.7°C (mean 15.4°C). It is one of the drier months, averaging 81 mm of rainfall and 84% 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 2023 — when the month averaged 17.5°C — while the coldest was 1986 at 13°C. Typical September days reach 17.1°C with nights near 13.7°C. The long-term trend is warming, about 0.2°C per decade.
September is one of the drier months in Truro, averaging 81 mm of rainfall. The wettest September on record was 2017 with 145 mm, while the driest was 2014 at 10 mm.
Relative humidity in Truro during September averages 84%. The most humid September was 1998 at 87%, and the least humid was 1990 at 78%.
September receives about 3.4 kWh/m²/day of solar energy in Truro. The sunniest Septembers were 1996 and 2014 at 3.9 kWh/m²/day, and the cloudiest was 2000 at 2.9.
Average wind speed in Truro during September is 5.5 m/s. The windiest September was 1983 at 6.8 m/s, while the calmest was 2014 at 3.8 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 15.0°C | 15.1°C | 15.5°C | 15.4°C | 16.1°C | +1.1°C |
| Avg High | 16.7°C | 16.8°C | 17.2°C | 17.0°C | 17.8°C | +1.1°C |
| Avg Low | 13.4°C | 13.4°C | 13.8°C | 13.8°C | 14.4°C | +1°C |
| Avg Rain | 80 mm | 89 mm | 60 mm | 83 mm | 101 mm | +21 mm |
September temperatures in Truro have risen by about 0.8°C between 1981–1985 and 2021–2025.
September has ranged from a record low of 9.3°C (1986) to a record high of 24.7°C (2023).
Rainfall in September is one of the drier months, averaging 81 mm, with a wettest year of 145 mm.
One of the best times to visit Truro
September is one of the best times to visit Truro. Expect days averaging 17.1°C and nights around 13.7°C (mean 15.4°C) — warmer than Truro's yearly average — with higher rainfall (81 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 | 17.1°C | 15.5°C | 14.0°C | 19.7°C | 10.8°C | 111 mm | 81% | 6.3 m/s | 3.5 |
| 2024 | 17.0°C | 15.4°C | 13.8°C | 21.7°C | 11.4°C | 121 mm | 84% | 5.6 m/s | 3 |
| 2023 🔥 | 19.3°C | 17.5°C | 15.6°C | 24.7°C | 12.9°C | 96 mm | 85% | 5.2 m/s | 3.4 |
| 2022 | 17.7°C | 16.1°C | 14.6°C | 21.3°C | 12.1°C | 110 mm | 82% | 5.8 m/s | 3.3 |
| 2021 | 18.6°C | 16.7°C | 14.8°C | 23.6°C | 12.5°C | 98 mm | 86% | 4.4 m/s | 3.1 |
| 2020 | 17.2°C | 15.5°C | 13.7°C | 21.3°C | 10.7°C | 70 mm | 83% | 5.2 m/s | 3.4 |
| 2019 | 17.4°C | 15.9°C | 14.3°C | 19.7°C | 12.5°C | 136 mm | 84% | 6.5 m/s | 3.5 |
| 2018 | 17.2°C | 15.4°C | 13.7°C | 21.6°C | 11.0°C | 67 mm | 82% | 5.5 m/s | 3.4 |
| 2017 🌧️ | 16.3°C | 14.9°C | 13.5°C | 19.0°C | 11.8°C | 145 mm | 84% | 6.6 m/s | 3.3 |
| 2016 | 17.5°C | 16.1°C | 14.8°C | 20.7°C | 12.6°C | 97 mm | 86% | 5.9 m/s | 3.1 |
| 2015 | 15.8°C | 14.2°C | 12.6°C | 18.8°C | 10.9°C | 65 mm | 83% | 5.5 m/s | 3.8 |
| 2014 | 18.6°C | 16.5°C | 14.4°C | 20.8°C | 12.2°C | 10 mm | 84% | 3.8 m/s | 3.9 |
| 2013 | 17.1°C | 15.5°C | 13.8°C | 20.0°C | 11.8°C | 60 mm | 84% | 5.2 m/s | 3 |
| 2012 | 16.0°C | 14.5°C | 13.0°C | 19.5°C | 9.9°C | 85 mm | 83% | 5.5 m/s | 3.4 |
| 2011 | 17.0°C | 15.5°C | 14.0°C | 19.6°C | 12.3°C | 71 mm | 85% | 6.6 m/s | 3.3 |
| 2010 | 16.8°C | 15.1°C | 13.4°C | 19.8°C | 10.1°C | 94 mm | 84% | 5.5 m/s | 3.5 |
| 2009 | 16.8°C | 15.0°C | 13.2°C | 19.3°C | 11.6°C | 41 mm | 84% | 5.2 m/s | 3.6 |
| 2008 | 16.3°C | 14.7°C | 13.2°C | 17.7°C | 11.9°C | 86 mm | 84% | 5.4 m/s | 3.5 |
| 2007 | 17.0°C | 15.3°C | 13.6°C | 20.4°C | 9.3°C | 37 mm | 84% | 5.2 m/s | 3.7 |
| 2006 | 18.6°C | 16.8°C | 15.0°C | 21.0°C | 13.7°C | 52 mm | 87% | 6 m/s | 3.5 |
| 2005 | 17.7°C | 16.0°C | 14.3°C | 21.4°C | 11.5°C | 71 mm | 84% | 5.2 m/s | 3.4 |
| 2004 | 17.3°C | 15.7°C | 14.1°C | 22.3°C | 11.9°C | 57 mm | 84% | 6.5 m/s | 3.5 |
| 2003 | 17.7°C | 15.7°C | 13.7°C | 20.6°C | 10.7°C | 36 mm | 81% | 4.6 m/s | 3.6 |
| 2002 | 17.4°C | 15.3°C | 13.3°C | 19.9°C | 10.8°C | 27 mm | 83% | 4.7 m/s | 3.8 |
| 2001 | 16.3°C | 14.9°C | 13.6°C | 18.4°C | 11.5°C | 45 mm | 84% | 5.9 m/s | 3.5 |
| 2000 | 17.3°C | 15.8°C | 14.2°C | 21.9°C | 11.5°C | 143 mm | 86% | 5.5 m/s | 2.9 |
| 1999 | 17.9°C | 16.2°C | 14.4°C | 22.1°C | 12.5°C | 119 mm | 84% | 5.6 m/s | 3.5 |
| 1998 | 17.1°C | 15.7°C | 14.2°C | 19.9°C | 12.4°C | 101 mm | 87% | 6.2 m/s | 3.3 |
| 1997 | 17.6°C | 15.6°C | 13.7°C | 19.6°C | 12.1°C | 35 mm | 86% | 5.1 m/s | 3.5 |
| 1996 | 16.8°C | 14.8°C | 12.7°C | 19.8°C | 10.4°C | 42 mm | 82% | 5.4 m/s | 3.9 |
| 1995 | 16.5°C | 15.0°C | 13.6°C | 18.9°C | 11.2°C | 101 mm | 82% | 5.9 m/s | 3.5 |
| 1994 | 15.5°C | 14.1°C | 12.7°C | 17.8°C | 10.6°C | 122 mm | 84% | 6 m/s | 3.1 |
| 1993 | 15.6°C | 14.0°C | 12.5°C | 19.6°C | 10.3°C | 140 mm | 83% | 5.6 m/s | 3.4 |
| 1992 | 15.6°C | 14.1°C | 12.6°C | 19.0°C | 11.0°C | 107 mm | 85% | 6 m/s | 3.2 |
| 1991 | 18.3°C | 16.3°C | 14.3°C | 22.2°C | 10.6°C | 68 mm | 81% | 4.9 m/s | 3.6 |
| 1990 | 17.1°C | 15.2°C | 13.3°C | 21.4°C | 11.2°C | 52 mm | 78% | 5.3 m/s | 3.7 |
| 1989 | 17.7°C | 15.9°C | 14.1°C | 20.7°C | 11.6°C | 74 mm | 82% | 5.2 m/s | 3 |
| 1988 | 15.7°C | 14.3°C | 12.8°C | 19.9°C | 9.7°C | 67 mm | 84% | 6 m/s | 3.2 |
| 1987 | 17.0°C | 15.4°C | 13.7°C | 20.0°C | 10.6°C | 73 mm | 83% | 5 m/s | 3.4 |
| 1986 ❄️ | 14.9°C | 13.0°C | 11.2°C | 16.4°C | 9.3°C | 26 mm | 82% | 4.2 m/s | 3.4 |
| 1985 | 17.0°C | 15.3°C | 13.5°C | 20.1°C | 11.1°C | 53 mm | 87% | 5.1 m/s | 3.4 |
| 1984 | 16.5°C | 15.0°C | 13.5°C | 21.0°C | 11.0°C | 109 mm | 79% | 6.1 m/s | 3.4 |
| 1983 | 16.6°C | 15.0°C | 13.4°C | 20.6°C | 11.1°C | 95 mm | 84% | 6.8 m/s | — |
| 1982 | 17.5°C | 15.7°C | 13.9°C | 22.6°C | 10.8°C | 87 mm | 85% | 4.9 m/s | — |
| 1981 | 17.5°C | 15.8°C | 14.1°C | 20.5°C | 12.0°C | 140 mm | 83% | 5.7 m/s | — |
Actual recorded September data for each year, 1981–2025 — sourced from NASA POWER.
The average high in September is around 17.1°C with lows near 13.7°C (mean 15.4°C), based on 45 years of NASA POWER data.
September averages 81 mm of rainfall in Truro, one of the drier months. The wettest on record was 145 mm in 2017.
The hottest September reached 24.7°C in 2023. The coldest dipped to 9.3°C in 1986.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average September temperatures have risen by about 0.8°C. Daytime highs moved from 17°C to 17.9°C and overnight lows from 13.7°C to 14.6°C over the same span.
September is one of the warmer months of the year in Truro and one of the drier months, so plan for around 17.1°C daytime highs and 13.7°C at night.
Not quite — September is the 10th coolest month in Truro, averaging 15.4°C.
For September in Truro, pack light layers you can adjust through the day, with typical highs of 17.1°C and lows of 13.7°C. Bring an umbrella or light rain jacket too.
Relative humidity in September averages 84% — quite humid.
Average wind speed in September is 5.5 m/s. The windiest September on record averaged 6.8 m/s (1983).
The wettest September on record was 2017 with 145 mm. On average, September sees 81 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.
