September is one of the warmer months of the year in Saint-Hyacinthe, with average highs near 21.1°C and lows around 10.1°C (mean 15.6°C). It is about average for rainfall, averaging 89 mm of rainfall and 78% relative humidity across the period.
September is one of the warmer months of the year in Saint-Hyacinthe. Across 45 years of records, the warmest September in Saint-Hyacinthe was 2015 — when the month averaged 18.5°C — while the coldest were 1986 and 1991 at 13°C. Typical September days reach 21.1°C with nights near 10.1°C. The long-term trend is warming, about 0.7°C per decade.
September is about average for rainfall in Saint-Hyacinthe, averaging 89 mm of rainfall. The wettest September on record was 1999 with 199 mm, while the driest was 2016 at 43 mm.
Relative humidity in Saint-Hyacinthe during September averages 78%. The most humid September was 2006 at 84%, and the least humid was 2025 at 70%.
September receives about 3.9 kWh/m²/day of solar energy in Saint-Hyacinthe. 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 Saint-Hyacinthe during September is 2.3 m/s. The windiest September was 1981 at 2.7 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 | 14.5°C | 14.7°C | 15.8°C | 16.5°C | 16.8°C | +2.3°C |
| Avg High | 20.0°C | 20.2°C | 21.4°C | 22.0°C | 22.4°C | +2.4°C |
| Avg Low | 9.0°C | 9.3°C | 10.2°C | 11.0°C | 11.2°C | +2.2°C |
| Avg Rain | 88 mm | 100 mm | 88 mm | 93 mm | 69 mm | -19 mm |
September temperatures in Saint-Hyacinthe have risen by about 2.4°C between 1981–1985 and 2021–2025.
September has ranged from a record low of -1.1°C (1991) to a record high of 33.7°C (2002).
Rainfall in September is about average for rainfall, averaging 89 mm, with a wettest year of 199 mm.
One of the best times to visit Saint-Hyacinthe
September is one of the best times to visit Saint-Hyacinthe. Expect days averaging 21.1°C and nights around 10.1°C (mean 15.6°C) — warmer than Saint-Hyacinthe's yearly average — with higher rainfall (89 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 | 23.2°C | 17.2°C | 11.2°C | 28.3°C | 3.7°C | 85 mm | 70% | 1.8 m/s | 4.5 |
| 2024 | 23.5°C | 17.9°C | 12.2°C | 28.7°C | 6.7°C | 45 mm | 77% | 2.1 m/s | 4.2 |
| 2023 | 23.0°C | 17.5°C | 12.0°C | 31.3°C | 5.8°C | 46 mm | 80% | 1.6 m/s | 4 |
| 2022 | 21.0°C | 15.6°C | 10.2°C | 29.3°C | 3.8°C | 111 mm | 77% | 2 m/s | 3.7 |
| 2021 | 23.2°C | 17.7°C | 12.2°C | 28.1°C | 6.6°C | 66 mm | 71% | 2.4 m/s | 3.7 |
| 2020 | 20.6°C | 15.1°C | 9.5°C | 26.9°C | 2.0°C | 62 mm | 74% | 2.5 m/s | 3.6 |
| 2019 | 21.0°C | 15.3°C | 9.7°C | 29.0°C | 3.3°C | 97 mm | 79% | 2.2 m/s | 3.8 |
| 2018 | 22.8°C | 17.4°C | 11.9°C | 32.3°C | 2.1°C | 101 mm | 77% | 2.3 m/s | 3.9 |
| 2017 | 23.2°C | 17.6°C | 12.1°C | 31.5°C | 5.3°C | 52 mm | 80% | 1.8 m/s | 4.2 |
| 2016 | 23.2°C | 17.2°C | 11.3°C | 29.9°C | 3.7°C | 43 mm | 75% | 2.1 m/s | 4.5 |
| 2015 🔥 | 24.3°C | 18.5°C | 12.6°C | 31.7°C | 3.7°C | 103 mm | 77% | 2.1 m/s | 4.3 |
| 2014 | 21.7°C | 15.7°C | 9.7°C | 30.1°C | -0.2°C | 53 mm | 77% | 2.4 m/s | 3.8 |
| 2013 | 20.0°C | 14.6°C | 9.1°C | 30.6°C | 3.6°C | 104 mm | 78% | 2.1 m/s | 3.8 |
| 2012 | 21.2°C | 15.6°C | 9.9°C | 27.8°C | 3.5°C | 106 mm | 76% | 2.5 m/s | 3.9 |
| 2011 | 21.9°C | 16.9°C | 12.0°C | 28.4°C | 3.7°C | 113 mm | 83% | 2 m/s | 3.7 |
| 2010 | 21.1°C | 16.3°C | 11.5°C | 32.4°C | 5.3°C | 158 mm | 80% | 2.5 m/s | 3.3 |
| 2009 | 20.5°C | 14.7°C | 8.8°C | 25.7°C | 2.2°C | 58 mm | 78% | 2.1 m/s | 4.3 |
| 2008 | 21.1°C | 15.7°C | 10.4°C | 29.2°C | 2.2°C | 61 mm | 82% | 2 m/s | 3.7 |
| 2007 | 22.1°C | 16.2°C | 10.3°C | 31.8°C | 4.0°C | 86 mm | 77% | 2.4 m/s | 4.4 |
| 2006 | 19.5°C | 14.4°C | 9.2°C | 24.9°C | 4.0°C | 80 mm | 84% | 2.2 m/s | 3.4 |
| 2005 | 21.9°C | 16.6°C | 11.3°C | 29.3°C | 3.7°C | 126 mm | 82% | 2.4 m/s | 4 |
| 2004 | 21.1°C | 15.6°C | 10.2°C | 26.6°C | 5.3°C | 92 mm | 82% | 2.2 m/s | 4.2 |
| 2003 | 22.7°C | 17.1°C | 11.5°C | 29.3°C | 5.6°C | 78 mm | 76% | 2.4 m/s | 4 |
| 2002 | 23.6°C | 17.5°C | 11.4°C | 33.7°C | 4.5°C | 131 mm | 74% | 2.4 m/s | 4.2 |
| 2001 | 21.8°C | 16.2°C | 10.6°C | 30.9°C | 3.3°C | 57 mm | 76% | 2.2 m/s | 4.1 |
| 2000 | 19.4°C | 14.0°C | 8.5°C | 28.5°C | -1.0°C | 106 mm | 80% | 2.5 m/s | 3.7 |
| 1999 🌧️ | 23.1°C | 17.6°C | 12.2°C | 33.1°C | 5.1°C | 199 mm | 78% | 2.4 m/s | 3.6 |
| 1998 | 21.2°C | 15.8°C | 10.4°C | 27.7°C | 3.1°C | 82 mm | 78% | 2.3 m/s | 3.8 |
| 1997 | 20.3°C | 14.7°C | 9.1°C | 26.0°C | 2.0°C | 55 mm | 76% | 2.6 m/s | 3.3 |
| 1996 | 21.4°C | 16.3°C | 11.3°C | 28.6°C | 4.4°C | 71 mm | 79% | 2.3 m/s | 3.7 |
| 1995 | 19.7°C | 13.5°C | 7.3°C | 27.0°C | 2.3°C | 76 mm | 71% | 2.2 m/s | 4 |
| 1994 | 19.8°C | 14.5°C | 9.3°C | 24.9°C | 5.4°C | 85 mm | 81% | 2.3 m/s | 3.6 |
| 1993 | 18.8°C | 13.5°C | 8.2°C | 28.1°C | -0.1°C | 116 mm | 79% | 2.4 m/s | 3.5 |
| 1992 | 19.8°C | 14.5°C | 9.2°C | 28.1°C | 0.4°C | 107 mm | 79% | 2.5 m/s | 3.6 |
| 1991 | 18.4°C | 13.0°C | 7.6°C | 28.1°C | -1.1°C | 108 mm | 76% | 2.2 m/s | 3.8 |
| 1990 | 19.2°C | 13.7°C | 8.2°C | 26.1°C | 3.1°C | 98 mm | 80% | 2.4 m/s | 3.2 |
| 1989 | 20.6°C | 15.0°C | 9.5°C | 30.1°C | 0.3°C | 104 mm | 78% | 2.3 m/s | 3.7 |
| 1988 | 19.7°C | 13.9°C | 8.1°C | 26.8°C | 0.6°C | 62 mm | 76% | 2.5 m/s | 3.8 |
| 1987 | 19.8°C | 14.5°C | 9.2°C | 26.9°C | -0.1°C | 118 mm | 79% | 2.4 m/s | 3.6 |
| 1986 ❄️ | 18.3°C | 13.0°C | 7.7°C | 23.6°C | 2.0°C | 133 mm | 81% | 2.3 m/s | 3.4 |
| 1985 | 21.3°C | 15.5°C | 9.7°C | 28.0°C | 3.2°C | 75 mm | 76% | 2.2 m/s | 4 |
| 1984 | 19.3°C | 13.5°C | 7.8°C | 26.7°C | 1.2°C | 48 mm | 75% | 2.3 m/s | 4.2 |
| 1983 | 22.5°C | 16.6°C | 10.7°C | 31.1°C | 4.4°C | 67 mm | 72% | 2.3 m/s | — |
| 1982 | 20.0°C | 14.6°C | 9.1°C | 28.9°C | 3.7°C | 92 mm | 81% | 2.1 m/s | — |
| 1981 | 18.9°C | 14.0°C | 9.1°C | 26.1°C | 0.4°C | 96 mm | 80% | 2.7 m/s | — |
Actual recorded September data for each year, 1981–2025 — sourced from NASA POWER.
The average high in September is around 21.1°C with lows near 10.1°C (mean 15.6°C), based on 45 years of NASA POWER data.
September averages 89 mm of rainfall in Saint-Hyacinthe, about average for rainfall. The wettest on record was 199 mm in 1999.
The hottest September reached 33.7°C in 2002. The coldest dipped to -1.1°C in 1991.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average September temperatures have risen by about 2.4°C. Daytime highs moved from 20.4°C to 22.8°C and overnight lows from 9.3°C to 11.6°C over the same span.
September is one of the warmer months of the year in Saint-Hyacinthe and about average for rainfall, so plan for around 21.1°C daytime highs and 10.1°C at night.
Not quite — September is the 9th coolest month in Saint-Hyacinthe, averaging 15.6°C.
For September in Saint-Hyacinthe, pack light layers you can adjust through the day, with typical highs of 21.1°C and lows of 10.1°C. Bring an umbrella or light rain jacket too.
Relative humidity in September averages 78% — quite humid.
Average wind speed in September is 2.3 m/s. The windiest September on record averaged 2.7 m/s (1981).
The wettest September on record was 1999 with 199 mm. On average, September sees 89 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 Saint-Hyacinthe 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.
