September is one of the warmer months of the year in Sudbury, with average highs near 19.8°C and lows around 8.4°C (mean 14.1°C). It is a relatively wet time of year, averaging 80 mm of rainfall and 76% relative humidity across the period.
September is one of the warmer months of the year in Sudbury. Across 45 years of records, the warmest September in Sudbury was 2024 — when the month averaged 17.4°C — while the coldest was 1993 at 11.1°C. Typical September days reach 19.8°C with nights near 8.4°C. The long-term trend is warming, about 0.6°C per decade.
September is a relatively wet time of year in Sudbury, averaging 80 mm of rainfall. The wettest September on record was 2001 with 174 mm, while the driest was 2004 at 31 mm.
Relative humidity in Sudbury during September averages 76%. The most humid September was 2014 at 83%, and the least humid was 2012 at 71%.
September receives about 3.7 kWh/m²/day of solar energy in Sudbury. The sunniest September was 2009 at 4.4 kWh/m²/day, and the cloudiest was 2010 at 3.
Average wind speed in Sudbury during September is 0.6 m/s. The windiest Septembers were 2000, 2001 and 2010, among others at 0.7 m/s, while the calmest were 2017, 2023 and 2025, 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 | 13.2°C | 13.4°C | 14.5°C | 14.6°C | 15.2°C | +2°C |
| Avg High | 18.7°C | 19.2°C | 20.2°C | 20.3°C | 21.1°C | +2.4°C |
| Avg Low | 7.7°C | 7.6°C | 8.8°C | 9.0°C | 9.3°C | +1.6°C |
| Avg Rain | 95 mm | 80 mm | 81 mm | 75 mm | 62 mm | -33 mm |
September temperatures in Sudbury have risen by about 2.7°C between 1981–1985 and 2021–2025.
September has ranged from a record low of -4°C (1981) to a record high of 31.7°C (2023).
Rainfall in September is a relatively wet time of year, averaging 80 mm, with a wettest year of 174 mm.
One of the best times to visit Sudbury
September is one of the best times to visit Sudbury. Expect days averaging 19.8°C and nights around 8.4°C (mean 14.1°C) — warmer than Sudbury's yearly average — with moderate rainfall (80 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 | 21.5°C | 15.2°C | 9.0°C | 26.7°C | 3.8°C | 43 mm | 74% | 0.5 m/s | 4 |
| 2024 🔥 | 23.7°C | 17.4°C | 11.1°C | 29.8°C | 5.5°C | 69 mm | 72% | 0.6 m/s | 4.1 |
| 2023 | 22.5°C | 16.3°C | 10.0°C | 31.7°C | 2.8°C | 35 mm | 73% | 0.5 m/s | 4.2 |
| 2022 | 20.9°C | 15.2°C | 9.4°C | 28.6°C | 0.5°C | 62 mm | 74% | 0.6 m/s | 3.8 |
| 2021 | 20.2°C | 14.5°C | 8.9°C | 25.6°C | 2.9°C | 82 mm | 75% | 0.6 m/s | 3.5 |
| 2020 | 18.0°C | 12.6°C | 7.2°C | 24.8°C | 0.1°C | 80 mm | 78% | 0.6 m/s | 3.4 |
| 2019 | 19.1°C | 13.9°C | 8.8°C | 26.2°C | 2.6°C | 115 mm | 80% | 0.6 m/s | 3.4 |
| 2018 | 20.9°C | 15.1°C | 9.3°C | 28.4°C | 0.7°C | 79 mm | 76% | 0.6 m/s | 3.7 |
| 2017 | 21.3°C | 15.5°C | 9.8°C | 29.6°C | 1.4°C | 54 mm | 80% | 0.5 m/s | 4.1 |
| 2016 | 22.2°C | 16.5°C | 10.7°C | 29.5°C | 3.5°C | 58 mm | 73% | 0.6 m/s | 3.9 |
| 2015 | 22.3°C | 16.8°C | 11.4°C | 27.9°C | 2.0°C | 61 mm | 78% | 0.6 m/s | 3.8 |
| 2014 | 18.0°C | 12.7°C | 7.4°C | 24.7°C | -1.0°C | 89 mm | 83% | 0.6 m/s | 3.4 |
| 2013 | 20.0°C | 13.9°C | 7.8°C | 27.6°C | -0.3°C | 76 mm | 72% | 0.6 m/s | 3.9 |
| 2012 | 19.7°C | 13.8°C | 7.9°C | 28.0°C | 1.0°C | 65 mm | 71% | 0.6 m/s | 3.9 |
| 2011 | 21.2°C | 15.0°C | 8.8°C | 30.0°C | -0.4°C | 47 mm | 71% | 0.6 m/s | 3.8 |
| 2010 | 18.0°C | 13.0°C | 8.1°C | 29.2°C | 2.8°C | 103 mm | 78% | 0.7 m/s | 3 |
| 2009 | 20.5°C | 14.4°C | 8.4°C | 25.6°C | 0.5°C | 53 mm | 75% | 0.5 m/s | 4.4 |
| 2008 | 19.6°C | 13.8°C | 8.0°C | 27.5°C | 1.3°C | 76 mm | 77% | 0.6 m/s | 4 |
| 2007 | 20.9°C | 15.1°C | 9.4°C | 28.0°C | 2.9°C | 46 mm | 74% | 0.6 m/s | 3.8 |
| 2006 | 18.3°C | 12.6°C | 7.0°C | 26.6°C | 1.2°C | 92 mm | 77% | 0.6 m/s | 3.3 |
| 2005 | 22.5°C | 16.3°C | 10.2°C | 30.8°C | 3.0°C | 77 mm | 72% | 0.6 m/s | 4 |
| 2004 | 22.6°C | 16.4°C | 10.2°C | 27.4°C | 2.3°C | 31 mm | 74% | 0.6 m/s | 4.3 |
| 2003 | 19.6°C | 14.3°C | 9.0°C | 28.4°C | 0.2°C | 113 mm | 78% | 0.6 m/s | 3.6 |
| 2002 | 22.0°C | 16.3°C | 10.6°C | 30.6°C | 4.1°C | 81 mm | 77% | 0.6 m/s | 3.9 |
| 2001 🌧️ | 17.8°C | 13.0°C | 8.2°C | 26.7°C | 2.0°C | 174 mm | 82% | 0.7 m/s | 3.2 |
| 2000 | 17.9°C | 12.4°C | 6.8°C | 24.8°C | -3.2°C | 66 mm | 75% | 0.7 m/s | 3.3 |
| 1999 | 21.3°C | 15.4°C | 9.5°C | 31.3°C | 1.2°C | 105 mm | 71% | 0.6 m/s | 4 |
| 1998 | 20.9°C | 14.9°C | 8.9°C | 30.2°C | 1.3°C | 91 mm | 74% | 0.6 m/s | 3.6 |
| 1997 | 19.1°C | 13.3°C | 7.5°C | 23.9°C | -0.1°C | 66 mm | 76% | 0.6 m/s | 3.5 |
| 1996 | 20.0°C | 14.7°C | 9.5°C | 30.3°C | 0.4°C | 124 mm | 79% | 0.6 m/s | 3.5 |
| 1995 | 17.6°C | 11.9°C | 6.1°C | 23.8°C | 0.0°C | 59 mm | 74% | 0.6 m/s | 3.6 |
| 1994 | 20.3°C | 14.5°C | 8.6°C | 26.0°C | 2.3°C | 45 mm | 76% | 0.5 m/s | 3.7 |
| 1993 ❄️ | 17.0°C | 11.1°C | 5.1°C | 25.8°C | -3.0°C | 66 mm | 73% | 0.6 m/s | 3.2 |
| 1992 | 18.8°C | 12.8°C | 6.7°C | 25.3°C | -2.2°C | 90 mm | 75% | 0.7 m/s | 3.2 |
| 1991 | 18.4°C | 12.6°C | 6.8°C | 27.8°C | -3.0°C | 82 mm | 72% | 0.6 m/s | 3.6 |
| 1990 | 18.1°C | 12.5°C | 6.9°C | 29.6°C | -1.1°C | 69 mm | 75% | 0.6 m/s | 3.3 |
| 1989 | 20.0°C | 13.8°C | 7.6°C | 26.8°C | -3.4°C | 45 mm | 72% | 0.6 m/s | 4 |
| 1988 | 19.1°C | 13.4°C | 7.6°C | 26.4°C | 2.6°C | 86 mm | 77% | 0.6 m/s | 3.8 |
| 1987 | 20.2°C | 14.6°C | 9.0°C | 27.2°C | 2.3°C | 86 mm | 74% | 0.6 m/s | 3.6 |
| 1986 | 17.1°C | 11.8°C | 6.6°C | 25.4°C | 0.2°C | 117 mm | 78% | 0.6 m/s | 3.4 |
| 1985 | 19.3°C | 13.8°C | 8.4°C | 28.5°C | 2.1°C | 67 mm | 79% | 0.6 m/s | 3.6 |
| 1984 | 16.6°C | 11.4°C | 6.2°C | 24.2°C | -0.6°C | 100 mm | 79% | 0.6 m/s | 3.8 |
| 1983 | 20.6°C | 15.0°C | 9.4°C | 29.0°C | 3.5°C | 106 mm | 77% | 0.6 m/s | — |
| 1982 | 17.8°C | 12.6°C | 7.4°C | 27.2°C | 0.7°C | 135 mm | 83% | 0.6 m/s | — |
| 1981 | 17.3°C | 12.0°C | 6.7°C | 26.3°C | -4.0°C | 117 mm | 78% | 0.6 m/s | — |
Actual recorded September data for each year, 1981–2025 — sourced from NASA POWER.
The average high in September is around 19.8°C with lows near 8.4°C (mean 14.1°C), based on 45 years of NASA POWER data.
September averages 80 mm of rainfall in Sudbury, a relatively wet time of year. The wettest on record was 174 mm in 2001.
The hottest September reached 31.7°C in 2023. The coldest dipped to -4°C in 1981.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average September temperatures have risen by about 2.7°C. Daytime highs moved from 18.3°C to 21.8°C and overnight lows from 7.6°C to 9.7°C over the same span.
September is one of the warmer months of the year in Sudbury and a relatively wet time of year, so plan for around 19.8°C daytime highs and 8.4°C at night.
Not quite — September is the 9th coolest month in Sudbury, averaging 14.1°C.
For September in Sudbury, pack light layers you can adjust through the day, with typical highs of 19.8°C and lows of 8.4°C. Bring an umbrella or light rain jacket too.
Relative humidity in September averages 76% — quite humid.
Average wind speed in September is 0.6 m/s. The windiest September on record averaged 0.7 m/s (1992).
The wettest September on record was 2001 with 174 mm. On average, September sees 80 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 Sudbury 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.
