September is one of the warmer months of the year in Belleville, with average highs near 27.7°C and lows around 14.7°C (mean 21.2°C). It is one of the drier months, averaging 80 mm of rainfall and 68% relative humidity across the period.
September is one of the warmer months of the year in Belleville. Across 45 years of records, the warmest September in Belleville was 2019 — when the month averaged 23.9°C — while the coldest was 1993 at 17.5°C. Typical September days reach 27.7°C with nights near 14.7°C. The long-term trend is warming, about 0.5°C per decade.
September is one of the drier months in Belleville, averaging 80 mm of rainfall. The wettest September on record was 1993 with 240 mm, while the driest was 2004 at 8 mm.
Relative humidity in Belleville during September averages 68%. The most humid September was 1993 at 81%, and the least humid was 1999 at 48%.
September receives about 4.7 kWh/m²/day of solar energy in Belleville. The sunniest September was 2004 at 5.4 kWh/m²/day, and the cloudiest was 1993 at 3.8.
Average wind speed in Belleville during September is 1.8 m/s. The windiest September was 1985 at 2.3 m/s, while the calmest was 2025 at 1.3 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 20.7°C | 20.6°C | 21.1°C | 21.6°C | 22.2°C | +1.5°C |
| Avg High | 27.2°C | 27.3°C | 27.7°C | 27.6°C | 29.0°C | +1.8°C |
| Avg Low | 14.2°C | 13.9°C | 14.5°C | 15.6°C | 15.4°C | +1.2°C |
| Avg Rain | 87 mm | 82 mm | 80 mm | 85 mm | 59 mm | -28 mm |
September temperatures in Belleville have risen by about 2.3°C between 1981–1985 and 2021–2025.
September has ranged from a record low of 0.7°C (1995) to a record high of 38.8°C (1990).
Rainfall in September is one of the drier months, averaging 80 mm, with a wettest year of 240 mm.
One of the best times to visit Belleville
September is one of the best times to visit Belleville. Expect days averaging 27.7°C and nights around 14.7°C (mean 21.2°C) — warmer than Belleville's yearly average — with higher 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 | 31.1°C | 23.7°C | 16.2°C | 37.5°C | 8.6°C | 39 mm | 57% | 1.3 m/s | 5.1 |
| 2024 | 28.8°C | 22.3°C | 15.7°C | 34.7°C | 7.6°C | 112 mm | 64% | 1.7 m/s | 4.6 |
| 2023 | 30.2°C | 23.2°C | 16.1°C | 34.4°C | 10.8°C | 43 mm | 63% | 1.6 m/s | 4.9 |
| 2022 | 28.3°C | 21.4°C | 14.6°C | 37.3°C | 5.0°C | 60 mm | 66% | 1.7 m/s | 4.9 |
| 2021 | 28.6°C | 22.1°C | 15.6°C | 32.9°C | 8.0°C | 69 mm | 70% | 1.9 m/s | 5.1 |
| 2020 | 26.8°C | 20.6°C | 14.3°C | 32.3°C | 6.1°C | 29 mm | 73% | 1.7 m/s | 4.5 |
| 2019 🔥 | 29.6°C | 23.9°C | 18.3°C | 33.1°C | 13.6°C | 27 mm | 77% | 1.7 m/s | 5 |
| 2018 | 27.8°C | 22.5°C | 17.2°C | 33.8°C | 8.6°C | 131 mm | 78% | 1.6 m/s | 4.8 |
| 2017 | 30.0°C | 22.9°C | 15.7°C | 35.7°C | 8.9°C | 21 mm | 60% | 1.7 m/s | 5 |
| 2016 | 27.4°C | 22.1°C | 16.9°C | 32.9°C | 9.4°C | 143 mm | 81% | 1.7 m/s | 4.9 |
| 2015 | 27.2°C | 21.6°C | 15.9°C | 32.9°C | 8.1°C | 71 mm | 74% | 1.6 m/s | 4.9 |
| 2014 | 26.7°C | 20.3°C | 14.0°C | 33.4°C | 6.2°C | 84 mm | 70% | 1.8 m/s | 4.8 |
| 2013 | 29.0°C | 22.3°C | 15.7°C | 36.6°C | 8.6°C | 38 mm | 68% | 1.6 m/s | 4.9 |
| 2012 | 26.0°C | 20.1°C | 14.1°C | 33.2°C | 5.2°C | 139 mm | 72% | 1.9 m/s | 4.4 |
| 2011 | 25.1°C | 19.0°C | 12.8°C | 38.4°C | 5.5°C | 87 mm | 67% | 1.9 m/s | 4.3 |
| 2010 | 27.0°C | 20.9°C | 14.9°C | 33.0°C | 7.5°C | 110 mm | 73% | 1.9 m/s | 4.7 |
| 2009 | 25.9°C | 20.2°C | 14.4°C | 28.8°C | 8.2°C | 76 mm | 76% | 1.6 m/s | 4.5 |
| 2008 | 25.4°C | 20.0°C | 14.5°C | 32.4°C | 9.4°C | 168 mm | 80% | 1.6 m/s | 4.3 |
| 2007 | 30.0°C | 23.2°C | 16.5°C | 36.5°C | 6.5°C | 60 mm | 61% | 1.7 m/s | 4.9 |
| 2006 | 26.2°C | 19.7°C | 13.2°C | 32.3°C | 5.4°C | 67 mm | 67% | 1.8 m/s | 4 |
| 2005 | 29.8°C | 23.4°C | 17.0°C | 34.9°C | 6.6°C | 133 mm | 67% | 1.6 m/s | 4.8 |
| 2004 | 28.3°C | 21.4°C | 14.5°C | 30.9°C | 7.8°C | 8 mm | 65% | 1.7 m/s | 5.4 |
| 2003 | 25.8°C | 19.2°C | 12.6°C | 32.1°C | 3.2°C | 90 mm | 69% | 1.9 m/s | 4.9 |
| 2002 | 30.0°C | 22.8°C | 15.6°C | 35.5°C | 6.6°C | 68 mm | 62% | 1.7 m/s | 4.9 |
| 2001 | 27.5°C | 20.5°C | 13.4°C | 34.8°C | 4.4°C | 61 mm | 63% | 1.9 m/s | 5.1 |
| 2000 | 28.3°C | 20.8°C | 13.4°C | 36.7°C | 4.0°C | 72 mm | 64% | 2.1 m/s | 4.9 |
| 1999 | 29.6°C | 21.7°C | 13.8°C | 36.9°C | 5.3°C | 30 mm | 48% | 1.8 m/s | 5.1 |
| 1998 | 29.9°C | 23.2°C | 16.5°C | 36.2°C | 10.1°C | 48 mm | 67% | 1.6 m/s | 4.7 |
| 1997 | 27.8°C | 21.0°C | 14.1°C | 34.3°C | 9.0°C | 53 mm | 64% | 1.8 m/s | 4.7 |
| 1996 | 26.5°C | 19.9°C | 13.4°C | 33.4°C | 5.7°C | 110 mm | 66% | 1.8 m/s | 4.4 |
| 1995 | 25.5°C | 18.9°C | 12.2°C | 32.0°C | 0.7°C | 23 mm | 64% | 1.8 m/s | 4.5 |
| 1994 | 27.0°C | 20.1°C | 13.3°C | 34.3°C | 7.0°C | 63 mm | 65% | 1.6 m/s | 4.6 |
| 1993 ❄️ 🌧️ | 22.8°C | 17.5°C | 12.1°C | 29.3°C | 4.3°C | 240 mm | 81% | 2 m/s | 3.8 |
| 1992 | 27.5°C | 20.4°C | 13.2°C | 33.6°C | 2.6°C | 98 mm | 67% | 1.9 m/s | 4.6 |
| 1991 | 26.8°C | 20.7°C | 14.6°C | 35.4°C | 3.7°C | 93 mm | 67% | 1.7 m/s | 4.7 |
| 1990 | 29.6°C | 22.7°C | 15.7°C | 38.8°C | 5.9°C | 63 mm | 64% | 1.8 m/s | 4.7 |
| 1989 | 25.8°C | 19.5°C | 13.3°C | 34.0°C | 2.5°C | 73 mm | 71% | 1.8 m/s | 4.2 |
| 1988 | 28.8°C | 21.6°C | 14.5°C | 33.9°C | 7.6°C | 94 mm | 64% | 2 m/s | 4.4 |
| 1987 | 28.7°C | 21.7°C | 14.7°C | 34.6°C | 9.5°C | 57 mm | 62% | 1.8 m/s | 4.6 |
| 1986 | 28.3°C | 22.6°C | 17.0°C | 32.1°C | 6.7°C | 165 mm | 73% | 1.9 m/s | 4.2 |
| 1985 | 26.6°C | 20.4°C | 14.2°C | 33.2°C | 3.9°C | 11 mm | 69% | 2.3 m/s | 4.7 |
| 1984 | 25.6°C | 19.3°C | 13.0°C | 37.9°C | 1.0°C | 203 mm | 69% | 2.2 m/s | 4.1 |
| 1983 | 29.5°C | 22.2°C | 14.8°C | 36.8°C | 2.0°C | 44 mm | 58% | 2 m/s | — |
| 1982 | 25.4°C | 19.4°C | 13.4°C | 30.5°C | 4.8°C | 89 mm | 76% | 1.7 m/s | — |
| 1981 | 26.2°C | 19.6°C | 13.0°C | 31.9°C | 6.2°C | 50 mm | 69% | 1.9 m/s | — |
Actual recorded September data for each year, 1981–2025 — sourced from NASA POWER.
The average high in September is around 27.7°C with lows near 14.7°C (mean 21.2°C), based on 45 years of NASA POWER data.
September averages 80 mm of rainfall in Belleville, one of the drier months. The wettest on record was 240 mm in 1993.
The hottest September reached 38.8°C in 1990. The coldest dipped to 0.7°C in 1995.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average September temperatures have risen by about 2.3°C. Daytime highs moved from 26.7°C to 29.4°C and overnight lows from 13.7°C to 15.6°C over the same span.
September is one of the warmer months of the year in Belleville and one of the drier months, so plan for around 27.7°C daytime highs and 14.7°C at night.
Not quite — September is the 9th coolest month in Belleville, averaging 21.2°C.
For September in Belleville, pack light layers you can adjust through the day, with typical highs of 27.7°C and lows of 14.7°C. Bring an umbrella or light rain jacket too.
Relative humidity in September averages 68% — moderately humid.
Average wind speed in September is 1.8 m/s. The windiest September on record averaged 2.3 m/s (1985).
The wettest September on record was 1993 with 240 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 Belleville 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.
