September is one of the warmer months of the year in L’Assomption, with average highs near 20.6°C and lows around 9.7°C (mean 15.2°C). It is about average for rainfall, averaging 84 mm of rainfall and 78% relative humidity across the period.
September is one of the warmer months of the year in L’Assomption. Across 45 years of records, the warmest September in L’Assomption was 2024 — when the month averaged 18°C — while the coldest were 1986 and 1991 at 12.5°C. Typical September days reach 20.6°C with nights near 9.7°C. The long-term trend is warming, about 0.7°C per decade.
September is about average for rainfall in L’Assomption, averaging 84 mm of rainfall. The wettest September on record was 2010 with 175 mm, while the driest was 2023 at 35 mm.
Relative humidity in L’Assomption during September averages 78%. The most humid September was 2006 at 83%, and the least humid was 1995 at 69%.
September receives about 3.9 kWh/m²/day of solar energy in L’Assomption. The sunniest Septembers were 2016 and 2025 at 4.5 kWh/m²/day, and the cloudiest was 1990 at 3.2.
Average wind speed in L’Assomption during September is 2.1 m/s. The windiest September was 1997 at 2.5 m/s, while the calmest was 2023 at 1.6 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 13.9°C | 14.5°C | 15.3°C | 15.9°C | 16.6°C | +2.7°C |
| Avg High | 19.4°C | 20.0°C | 20.8°C | 21.2°C | 22.3°C | +2.9°C |
| Avg Low | 8.6°C | 9.1°C | 9.9°C | 10.6°C | 10.9°C | +2.3°C |
| Avg Rain | 89 mm | 83 mm | 89 mm | 92 mm | 57 mm | -31 mm |
September temperatures in L’Assomption have risen by about 2.8°C between 1981–1985 and 2021–2025.
September has ranged from a record low of -2°C (1991) to a record high of 32.2°C (2023).
Rainfall in September is about average for rainfall, averaging 84 mm, with a wettest year of 175 mm.
One of the best times to visit L’Assomption
September is one of the best times to visit L’Assomption. Expect days averaging 20.6°C and nights around 9.7°C (mean 15.2°C) — warmer than L’Assomption'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 | 23.0°C | 16.9°C | 10.8°C | 28.3°C | 3.2°C | 68 mm | 70% | 1.8 m/s | 4.5 |
| 2024 🔥 | 23.8°C | 18.0°C | 12.2°C | 29.7°C | 6.5°C | 38 mm | 75% | 2.1 m/s | 4.2 |
| 2023 | 23.6°C | 17.9°C | 12.2°C | 32.2°C | 6.1°C | 35 mm | 76% | 1.6 m/s | 4 |
| 2022 | 20.9°C | 15.4°C | 9.8°C | 28.9°C | 3.6°C | 92 mm | 74% | 2 m/s | 3.7 |
| 2021 | 22.4°C | 16.9°C | 11.5°C | 26.9°C | 5.8°C | 56 mm | 73% | 2.2 m/s | 3.7 |
| 2020 | 19.8°C | 14.4°C | 8.9°C | 25.6°C | 2.2°C | 56 mm | 75% | 2.2 m/s | 3.6 |
| 2019 | 20.1°C | 14.7°C | 9.3°C | 27.1°C | 2.7°C | 105 mm | 80% | 2 m/s | 3.8 |
| 2018 | 21.6°C | 16.3°C | 11.1°C | 29.9°C | 0.9°C | 101 mm | 79% | 2 m/s | 3.9 |
| 2017 | 22.5°C | 17.3°C | 12.1°C | 30.0°C | 5.1°C | 44 mm | 81% | 1.7 m/s | 4.2 |
| 2016 | 22.2°C | 16.7°C | 11.1°C | 29.0°C | 3.9°C | 39 mm | 76% | 2 m/s | 4.5 |
| 2015 | 23.2°C | 17.8°C | 12.4°C | 30.3°C | 3.7°C | 105 mm | 79% | 2 m/s | 4.3 |
| 2014 | 20.2°C | 14.7°C | 9.3°C | 27.7°C | -0.5°C | 62 mm | 81% | 2.2 m/s | 3.8 |
| 2013 | 19.4°C | 14.2°C | 8.9°C | 28.0°C | 3.1°C | 91 mm | 79% | 2.1 m/s | 3.8 |
| 2012 | 20.6°C | 15.1°C | 9.6°C | 26.4°C | 3.4°C | 91 mm | 77% | 2.3 m/s | 3.9 |
| 2011 | 21.5°C | 16.5°C | 11.5°C | 27.4°C | 4.1°C | 103 mm | 82% | 1.8 m/s | 3.7 |
| 2010 🌧️ | 20.3°C | 15.7°C | 11.1°C | 31.7°C | 5.9°C | 175 mm | 81% | 2.4 m/s | 3.3 |
| 2009 | 19.8°C | 14.2°C | 8.7°C | 24.7°C | 2.0°C | 59 mm | 79% | 1.9 m/s | 4.3 |
| 2008 | 20.9°C | 15.5°C | 10.0°C | 28.8°C | 2.1°C | 65 mm | 81% | 1.9 m/s | 3.7 |
| 2007 | 21.4°C | 15.6°C | 9.8°C | 30.3°C | 3.6°C | 83 mm | 78% | 2.2 m/s | 4.4 |
| 2006 | 19.0°C | 14.0°C | 8.9°C | 24.0°C | 3.7°C | 87 mm | 83% | 2.1 m/s | 3.4 |
| 2005 | 21.4°C | 16.1°C | 10.8°C | 28.1°C | 3.8°C | 137 mm | 81% | 2.3 m/s | 4 |
| 2004 | 20.7°C | 15.3°C | 9.9°C | 25.6°C | 5.0°C | 102 mm | 81% | 2.1 m/s | 4.2 |
| 2003 | 21.9°C | 16.5°C | 11.1°C | 27.6°C | 5.8°C | 96 mm | 79% | 2.2 m/s | 4 |
| 2002 | 22.7°C | 16.9°C | 11.0°C | 32.0°C | 4.3°C | 99 mm | 76% | 2.2 m/s | 4.2 |
| 2001 | 21.3°C | 15.8°C | 10.4°C | 30.0°C | 3.9°C | 64 mm | 77% | 2.1 m/s | 4.1 |
| 2000 | 18.6°C | 13.3°C | 8.0°C | 26.9°C | -1.6°C | 102 mm | 80% | 2.3 m/s | 3.7 |
| 1999 | 22.4°C | 17.2°C | 12.0°C | 31.6°C | 4.8°C | 165 mm | 79% | 2.2 m/s | 3.6 |
| 1998 | 21.2°C | 15.6°C | 10.1°C | 26.8°C | 3.4°C | 58 mm | 75% | 2.2 m/s | 3.8 |
| 1997 | 20.4°C | 14.8°C | 9.1°C | 26.6°C | 1.5°C | 55 mm | 75% | 2.5 m/s | 3.3 |
| 1996 | 21.5°C | 16.4°C | 11.2°C | 30.0°C | 3.8°C | 62 mm | 75% | 2.2 m/s | 3.7 |
| 1995 | 19.5°C | 13.2°C | 6.9°C | 27.4°C | 2.0°C | 49 mm | 69% | 2.1 m/s | 4 |
| 1994 | 20.2°C | 14.7°C | 9.2°C | 24.4°C | 5.2°C | 67 mm | 77% | 2.1 m/s | 3.6 |
| 1993 | 18.9°C | 13.5°C | 8.1°C | 27.9°C | -0.1°C | 98 mm | 76% | 2.3 m/s | 3.5 |
| 1992 | 19.2°C | 14.1°C | 8.9°C | 27.1°C | 0.1°C | 92 mm | 79% | 2.3 m/s | 3.6 |
| 1991 | 17.9°C | 12.5°C | 7.1°C | 25.5°C | -2.0°C | 77 mm | 76% | 2 m/s | 3.8 |
| 1990 | 18.5°C | 13.3°C | 8.0°C | 25.8°C | 2.6°C | 103 mm | 80% | 2.2 m/s | 3.2 |
| 1989 | 20.4°C | 14.8°C | 9.3°C | 28.7°C | 0.1°C | 85 mm | 78% | 2.1 m/s | 3.7 |
| 1988 | 18.8°C | 13.2°C | 7.7°C | 25.3°C | 0.5°C | 62 mm | 78% | 2.3 m/s | 3.8 |
| 1987 | 19.1°C | 13.9°C | 8.8°C | 25.7°C | -0.5°C | 127 mm | 81% | 2.3 m/s | 3.6 |
| 1986 ❄️ | 17.8°C | 12.5°C | 7.2°C | 24.3°C | 1.1°C | 139 mm | 80% | 2.1 m/s | 3.4 |
| 1985 | 20.7°C | 15.0°C | 9.2°C | 27.3°C | 3.0°C | 79 mm | 78% | 2 m/s | 4 |
| 1984 | 18.5°C | 12.7°C | 7.0°C | 24.8°C | 0.8°C | 38 mm | 77% | 2.2 m/s | 4.2 |
| 1983 | 21.5°C | 15.8°C | 10.2°C | 29.9°C | 3.6°C | 72 mm | 76% | 2.2 m/s | — |
| 1982 | 19.3°C | 14.0°C | 8.8°C | 27.0°C | 3.6°C | 97 mm | 82% | 2 m/s | — |
| 1981 | 18.3°C | 13.6°C | 8.8°C | 24.8°C | 0.5°C | 99 mm | 81% | 2.4 m/s | — |
Actual recorded September data for each year, 1981–2025 — sourced from NASA POWER.
The average high in September is around 20.6°C with lows near 9.7°C (mean 15.2°C), based on 45 years of NASA POWER data.
September averages 84 mm of rainfall in L’Assomption, about average for rainfall. The wettest on record was 175 mm in 2010.
The hottest September reached 32.2°C in 2023. The coldest dipped to -2°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 19.7°C to 22.7°C and overnight lows from 8.8°C to 11.3°C over the same span.
September is one of the warmer months of the year in L’Assomption and about average for rainfall, so plan for around 20.6°C daytime highs and 9.7°C at night.
Not quite — September is the 9th coolest month in L’Assomption, averaging 15.2°C.
For September in L’Assomption, pack light layers you can adjust through the day, with typical highs of 20.6°C and lows of 9.7°C. Bring an umbrella or light rain jacket too.
Relative humidity in September averages 78% — quite humid.
Average wind speed in September is 2.1 m/s. The windiest September on record averaged 2.5 m/s (1997).
The wettest September on record was 2010 with 175 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 L’Assomption 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.
