September is one of the warmer months of the year in Joliette, with average highs near 19.8°C and lows around 8.7°C (mean 14.3°C). It is about average for rainfall, averaging 84 mm of rainfall and 79% relative humidity across the period.
September is one of the warmer months of the year in Joliette. Across 45 years of records, the warmest September in Joliette was 2023 — when the month averaged 17.3°C — while the coldest were 1986 and 1991 at 11.5°C. Typical September days reach 19.8°C with nights near 8.7°C. The long-term trend is warming, about 0.7°C per decade.
September is about average for rainfall in Joliette, averaging 84 mm of rainfall. The wettest September on record was 2010 with 176 mm, while the driest was 2023 at 26 mm.
Relative humidity in Joliette during September averages 79%. The most humid September was 2006 at 84%, and the least humid was 1995 at 66%.
September receives about 3.7 kWh/m²/day of solar energy in Joliette. The sunniest September was 2025 at 4.4 kWh/m²/day, and the cloudiest was 2010 at 3.1.
Average wind speed in Joliette during September is 0.9 m/s. The windiest Septembers were 1981 and 1997 at 1.1 m/s, while the calmest were 2019, 2023 and 2025, among others at 0.8 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 13.0°C | 13.7°C | 14.5°C | 15.0°C | 15.7°C | +2.7°C |
| Avg High | 18.4°C | 19.4°C | 20.1°C | 20.3°C | 21.5°C | +3.1°C |
| Avg Low | 7.7°C | 8.1°C | 8.8°C | 9.6°C | 9.8°C | +2.1°C |
| Avg Rain | 91 mm | 73 mm | 96 mm | 95 mm | 55 mm | -36 mm |
September temperatures in Joliette have risen by about 2.8°C between 1981–1985 and 2021–2025.
September has ranged from a record low of -3.7°C (1991) to a record high of 32.7°C (2023).
Rainfall in September is about average for rainfall, averaging 84 mm, with a wettest year of 176 mm.
One of the best times to visit Joliette
September is one of the best times to visit Joliette. Expect days averaging 19.8°C and nights around 8.7°C (mean 14.3°C) — warmer than Joliette's yearly average — with higher rainfall (84 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 | 22.8°C | 16.2°C | 9.7°C | 27.8°C | 2.0°C | 43 mm | 69% | 0.8 m/s | 4.4 |
| 2024 | 22.8°C | 17.0°C | 11.2°C | 28.7°C | 5.6°C | 47 mm | 77% | 0.9 m/s | 4 |
| 2023 🔥 | 23.4°C | 17.3°C | 11.2°C | 32.7°C | 5.7°C | 26 mm | 76% | 0.8 m/s | 4.1 |
| 2022 | 19.8°C | 14.2°C | 8.6°C | 28.2°C | 2.4°C | 85 mm | 76% | 0.9 m/s | 3.9 |
| 2021 | 21.3°C | 15.8°C | 10.3°C | 27.0°C | 3.8°C | 71 mm | 75% | 1 m/s | 3.6 |
| 2020 | 18.9°C | 13.4°C | 8.0°C | 24.9°C | 1.6°C | 56 mm | 77% | 1 m/s | 3.4 |
| 2019 | 19.5°C | 14.0°C | 8.5°C | 25.6°C | 1.6°C | 103 mm | 82% | 0.8 m/s | 3.5 |
| 2018 | 20.9°C | 15.5°C | 10.0°C | 29.5°C | -0.2°C | 117 mm | 81% | 0.9 m/s | 3.7 |
| 2017 | 21.8°C | 16.5°C | 11.2°C | 29.9°C | 3.9°C | 47 mm | 83% | 0.8 m/s | 4 |
| 2016 | 21.3°C | 15.7°C | 10.1°C | 28.3°C | 3.2°C | 44 mm | 77% | 0.9 m/s | 4.2 |
| 2015 | 22.5°C | 16.9°C | 11.3°C | 29.4°C | 2.5°C | 106 mm | 80% | 0.9 m/s | 4.1 |
| 2014 | 19.3°C | 13.7°C | 8.1°C | 27.0°C | -1.9°C | 64 mm | 82% | 1 m/s | 3.5 |
| 2013 | 18.5°C | 13.2°C | 7.9°C | 27.0°C | 1.8°C | 99 mm | 81% | 0.9 m/s | 3.7 |
| 2012 | 19.6°C | 14.0°C | 8.4°C | 27.1°C | 1.7°C | 98 mm | 78% | 1 m/s | 3.7 |
| 2011 | 20.7°C | 15.6°C | 10.4°C | 27.2°C | 3.3°C | 101 mm | 83% | 0.8 m/s | 3.7 |
| 2010 🌧️ | 19.2°C | 14.5°C | 9.8°C | 31.2°C | 4.1°C | 176 mm | 83% | 1 m/s | 3.1 |
| 2009 | 19.0°C | 13.4°C | 7.8°C | 24.4°C | 0.9°C | 61 mm | 80% | 0.8 m/s | 4.2 |
| 2008 | 20.4°C | 14.7°C | 8.9°C | 29.0°C | 0.6°C | 56 mm | 82% | 0.8 m/s | 3.6 |
| 2007 | 20.7°C | 14.7°C | 8.8°C | 29.8°C | 2.8°C | 71 mm | 79% | 1 m/s | 4.2 |
| 2006 | 18.2°C | 13.1°C | 7.9°C | 23.3°C | 1.9°C | 107 mm | 84% | 0.9 m/s | 3.4 |
| 2005 | 20.8°C | 15.3°C | 9.8°C | 27.6°C | 2.7°C | 148 mm | 82% | 1 m/s | 3.8 |
| 2004 | 20.2°C | 14.6°C | 9.0°C | 24.6°C | 4.0°C | 118 mm | 82% | 0.9 m/s | 4 |
| 2003 | 20.9°C | 15.5°C | 10.0°C | 26.8°C | 4.7°C | 134 mm | 81% | 1 m/s | 3.8 |
| 2002 | 22.2°C | 16.1°C | 10.1°C | 31.6°C | 3.3°C | 83 mm | 76% | 0.9 m/s | 4.2 |
| 2001 | 20.6°C | 14.9°C | 9.2°C | 30.3°C | 3.2°C | 80 mm | 77% | 0.9 m/s | 3.8 |
| 2000 | 17.6°C | 12.2°C | 6.8°C | 26.1°C | -3.0°C | 99 mm | 82% | 1 m/s | 3.4 |
| 1999 | 21.8°C | 16.4°C | 10.9°C | 32.1°C | 3.7°C | 137 mm | 79% | 1 m/s | 3.4 |
| 1998 | 20.6°C | 14.8°C | 9.0°C | 26.4°C | 2.0°C | 52 mm | 76% | 1 m/s | 3.7 |
| 1997 | 19.5°C | 13.8°C | 8.1°C | 26.4°C | 0.4°C | 70 mm | 75% | 1.1 m/s | 3.2 |
| 1996 | 21.3°C | 15.9°C | 10.5°C | 30.3°C | 3.0°C | 64 mm | 74% | 1 m/s | 3.5 |
| 1995 | 19.4°C | 12.6°C | 5.9°C | 27.0°C | 0.3°C | 41 mm | 66% | 1 m/s | 3.9 |
| 1994 | 20.1°C | 14.3°C | 8.5°C | 24.2°C | 4.2°C | 55 mm | 75% | 0.9 m/s | 3.4 |
| 1993 | 18.4°C | 12.7°C | 7.1°C | 27.8°C | -1.0°C | 75 mm | 73% | 1 m/s | 3.3 |
| 1992 | 18.2°C | 12.9°C | 7.7°C | 26.3°C | -1.0°C | 73 mm | 80% | 1 m/s | 3.4 |
| 1991 | 17.1°C | 11.5°C | 5.9°C | 25.4°C | -3.7°C | 66 mm | 76% | 0.9 m/s | 3.7 |
| 1990 | 17.6°C | 12.3°C | 6.9°C | 25.0°C | 1.2°C | 96 mm | 81% | 1 m/s | 3.3 |
| 1989 | 19.6°C | 13.9°C | 8.3°C | 27.2°C | -0.7°C | 88 mm | 79% | 0.9 m/s | 3.7 |
| 1988 | 17.8°C | 12.3°C | 6.8°C | 25.3°C | 0.3°C | 65 mm | 80% | 1 m/s | 3.6 |
| 1987 | 18.1°C | 13.1°C | 8.1°C | 25.2°C | -1.9°C | 130 mm | 83% | 1 m/s | 3.4 |
| 1986 ❄️ | 16.9°C | 11.5°C | 6.2°C | 23.8°C | 0.9°C | 138 mm | 82% | 0.9 m/s | 3.3 |
| 1985 | 19.8°C | 14.1°C | 8.3°C | 26.6°C | 2.5°C | 77 mm | 78% | 0.9 m/s | 4 |
| 1984 | 17.5°C | 11.8°C | 6.0°C | 23.9°C | -0.2°C | 32 mm | 79% | 0.9 m/s | 4.3 |
| 1983 | 20.7°C | 15.0°C | 9.3°C | 29.4°C | 2.5°C | 74 mm | 77% | 1 m/s | — |
| 1982 | 18.5°C | 13.2°C | 8.0°C | 26.3°C | 3.2°C | 102 mm | 83% | 0.9 m/s | — |
| 1981 | 17.1°C | 12.5°C | 7.9°C | 23.2°C | -0.3°C | 108 mm | 83% | 1.1 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 8.7°C (mean 14.3°C), based on 45 years of NASA POWER data.
September averages 84 mm of rainfall in Joliette, about average for rainfall. The wettest on record was 176 mm in 2010.
The hottest September reached 32.7°C in 2023. The coldest dipped to -3.7°C in 1991.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average September temperatures have risen by about 2.8°C. Daytime highs moved from 18.7°C to 22°C and overnight lows from 7.9°C to 10.2°C over the same span.
September is one of the warmer months of the year in Joliette and about average for rainfall, so plan for around 19.8°C daytime highs and 8.7°C at night.
Not quite — September is the 9th coolest month in Joliette, averaging 14.3°C.
For September in Joliette, pack light layers you can adjust through the day, with typical highs of 19.8°C and lows of 8.7°C. Bring an umbrella or light rain jacket too.
Relative humidity in September averages 79% — quite humid.
Average wind speed in September is 0.9 m/s. The windiest September on record averaged 1.1 m/s (1981).
The wettest September on record was 2010 with 176 mm. On average, September sees 84 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 Joliette 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.
