September is one of the warmer months of the year in Rimouski, with average highs near 15.3°C and lows around 8.6°C (mean 12°C). It is about average for rainfall, averaging 82 mm of rainfall and 82% relative humidity across the period.
September is one of the warmer months of the year in Rimouski. Across 45 years of records, the warmest September in Rimouski was 2023 — when the month averaged 15.2°C — while the coldest was 1986 at 9.2°C. Typical September days reach 15.3°C with nights near 8.6°C. The long-term trend is warming, about 0.5°C per decade.
September is about average for rainfall in Rimouski, averaging 82 mm of rainfall. The wettest September on record was 2010 with 228 mm, while the driest was 2025 at 25 mm.
Relative humidity in Rimouski during September averages 82%. The most humid Septembers were 1987 and 2010 at 85%, and the least humid was 1995 at 77%.
September receives about 3.5 kWh/m²/day of solar energy in Rimouski. The sunniest Septembers were 1989 and 2025 at 4 kWh/m²/day, and the cloudiest was 1997 at 2.8.
Average wind speed in Rimouski during September is 1.9 m/s. The windiest Septembers were 1988 and 2000 at 2.3 m/s, while the calmest was 2017 at 1.5 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 10.9°C | 11.7°C | 12.1°C | 12.2°C | 13.2°C | +2.3°C |
| Avg High | 14.2°C | 15.0°C | 15.5°C | 15.4°C | 16.8°C | +2.6°C |
| Avg Low | 7.6°C | 8.3°C | 8.8°C | 8.9°C | 9.6°C | +2°C |
| Avg Rain | 74 mm | 79 mm | 99 mm | 94 mm | 54 mm | -19 mm |
September temperatures in Rimouski have risen by about 2.4°C between 1981–1985 and 2021–2025.
September has ranged from a record low of 0°C (2000) to a record high of 27°C (1999).
Rainfall in September is about average for rainfall, averaging 82 mm, with a wettest year of 228 mm.
One of the best times to visit Rimouski
September is one of the best times to visit Rimouski. Expect days averaging 15.3°C and nights around 8.6°C (mean 12°C) — warmer than Rimouski's yearly average — with higher rainfall (82 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 | 16.9°C | 12.9°C | 8.9°C | 22.9°C | 4.8°C | 25 mm | 77% | 1.7 m/s | 4 |
| 2024 | 18.1°C | 14.1°C | 10.1°C | 24.0°C | 7.4°C | 36 mm | 78% | 1.7 m/s | 3.8 |
| 2023 🔥 | 18.7°C | 15.2°C | 11.6°C | 25.5°C | 6.7°C | 54 mm | 81% | 1.6 m/s | 3.7 |
| 2022 | 16.1°C | 12.6°C | 9.1°C | 23.3°C | 5.6°C | 31 mm | 78% | 1.7 m/s | 3.9 |
| 2021 | 16.1°C | 13.0°C | 9.9°C | 20.4°C | 6.4°C | 130 mm | 83% | 1.9 m/s | 3.3 |
| 2020 | 14.6°C | 11.2°C | 7.8°C | 19.9°C | 2.1°C | 50 mm | 81% | 2.1 m/s | 3.6 |
| 2019 | 13.4°C | 10.4°C | 7.4°C | 18.5°C | 1.9°C | 104 mm | 84% | 1.8 m/s | 3.2 |
| 2018 | 15.4°C | 11.9°C | 8.4°C | 24.0°C | 1.2°C | 77 mm | 82% | 2 m/s | 3.7 |
| 2017 | 16.1°C | 12.9°C | 9.6°C | 22.9°C | 3.2°C | 72 mm | 85% | 1.5 m/s | 3.3 |
| 2016 | 16.0°C | 12.6°C | 9.2°C | 22.9°C | 4.8°C | 71 mm | 83% | 1.8 m/s | 3.6 |
| 2015 | 17.3°C | 13.9°C | 10.5°C | 23.0°C | 3.3°C | 60 mm | 83% | 1.8 m/s | 3.8 |
| 2014 | 14.8°C | 11.6°C | 8.3°C | 22.5°C | 2.6°C | 85 mm | 81% | 2.2 m/s | 3.5 |
| 2013 | 14.3°C | 11.2°C | 8.1°C | 17.8°C | 4.6°C | 96 mm | 85% | 2 m/s | 3.2 |
| 2012 | 16.0°C | 12.5°C | 9.0°C | 22.1°C | 4.3°C | 52 mm | 82% | 1.9 m/s | 3.6 |
| 2011 | 16.2°C | 12.8°C | 9.5°C | 20.1°C | 5.7°C | 94 mm | 84% | 1.8 m/s | 3.8 |
| 2010 🌧️ | 14.3°C | 11.7°C | 9.1°C | 26.3°C | 4.7°C | 228 mm | 85% | 2 m/s | 3 |
| 2009 | 15.0°C | 11.6°C | 8.2°C | 20.6°C | 3.0°C | 58 mm | 82% | 1.8 m/s | 3.8 |
| 2008 | 15.0°C | 11.8°C | 8.7°C | 22.3°C | 1.8°C | 118 mm | 85% | 1.7 m/s | 3.3 |
| 2007 | 14.7°C | 11.4°C | 8.0°C | 24.2°C | 2.6°C | 122 mm | 82% | 2.2 m/s | 3.6 |
| 2006 | 15.2°C | 11.8°C | 8.4°C | 20.8°C | 5.1°C | 119 mm | 82% | 1.8 m/s | 3.6 |
| 2005 | 15.7°C | 12.6°C | 9.5°C | 21.1°C | 5.8°C | 129 mm | 84% | 2.1 m/s | 3.5 |
| 2004 | 14.7°C | 11.5°C | 8.3°C | 19.1°C | 4.6°C | 113 mm | 85% | 1.9 m/s | 3.7 |
| 2003 | 17.4°C | 13.7°C | 10.1°C | 23.8°C | 6.1°C | 94 mm | 82% | 1.7 m/s | 3.7 |
| 2002 | 16.7°C | 13.0°C | 9.3°C | 23.0°C | 3.9°C | 99 mm | 81% | 1.9 m/s | 3.6 |
| 2001 | 15.9°C | 12.6°C | 9.3°C | 24.4°C | 4.3°C | 77 mm | 82% | 1.9 m/s | 3.8 |
| 2000 | 14.4°C | 11.3°C | 8.1°C | 19.1°C | 0.0°C | 63 mm | 81% | 2.3 m/s | 3.3 |
| 1999 | 18.2°C | 14.8°C | 11.5°C | 27.0°C | 6.4°C | 128 mm | 81% | 1.9 m/s | 3.5 |
| 1998 | 15.5°C | 12.5°C | 9.5°C | 20.1°C | 4.3°C | 97 mm | 81% | 2.1 m/s | 3.2 |
| 1997 | 15.1°C | 12.0°C | 8.9°C | 21.5°C | 3.7°C | 38 mm | 79% | 2.1 m/s | 2.8 |
| 1996 | 15.2°C | 11.9°C | 8.5°C | 23.3°C | 4.2°C | 47 mm | 80% | 1.8 m/s | 3.5 |
| 1995 | 14.2°C | 10.4°C | 6.7°C | 19.7°C | 1.5°C | 49 mm | 77% | 2.1 m/s | 3.6 |
| 1994 | 14.3°C | 11.0°C | 7.8°C | 19.7°C | 4.3°C | 73 mm | 85% | 1.7 m/s | 3.5 |
| 1993 | 14.1°C | 10.7°C | 7.2°C | 19.8°C | 1.6°C | 116 mm | 81% | 2.1 m/s | 3.2 |
| 1992 | 15.4°C | 11.9°C | 8.5°C | 22.0°C | 2.2°C | 77 mm | 83% | 2.1 m/s | 3.4 |
| 1991 | 13.7°C | 10.4°C | 7.1°C | 19.3°C | 1.0°C | 57 mm | 80% | 2.1 m/s | 3.5 |
| 1990 | 14.6°C | 11.1°C | 7.6°C | 20.1°C | 2.8°C | 106 mm | 78% | 2.2 m/s | 3.5 |
| 1989 | 15.7°C | 11.9°C | 8.2°C | 23.2°C | 2.1°C | 49 mm | 79% | 2.2 m/s | 4 |
| 1988 | 13.4°C | 10.3°C | 7.2°C | 18.9°C | 3.3°C | 87 mm | 81% | 2.3 m/s | 3.4 |
| 1987 | 13.9°C | 10.8°C | 7.7°C | 21.5°C | 2.2°C | 95 mm | 85% | 2 m/s | 3.3 |
| 1986 ❄️ | 12.4°C | 9.2°C | 5.9°C | 18.3°C | 1.6°C | 100 mm | 81% | 2.1 m/s | 3.4 |
| 1985 | 15.4°C | 12.0°C | 8.7°C | 21.2°C | 4.5°C | 68 mm | 81% | 1.8 m/s | 3.5 |
| 1984 | 13.1°C | 9.9°C | 6.6°C | 19.7°C | 2.0°C | 48 mm | 81% | 2.2 m/s | 3.8 |
| 1983 | 15.3°C | 11.9°C | 8.6°C | 22.9°C | 4.3°C | 75 mm | 84% | 1.8 m/s | — |
| 1982 | 14.0°C | 10.8°C | 7.5°C | 21.3°C | 2.3°C | 83 mm | 84% | 1.7 m/s | — |
| 1981 | 14.7°C | 11.5°C | 8.4°C | 22.2°C | 4.2°C | 59 mm | 83% | 2.2 m/s | — |
Actual recorded September data for each year, 1981–2025 — sourced from NASA POWER.
The average high in September is around 15.3°C with lows near 8.6°C (mean 12°C), based on 45 years of NASA POWER data.
September averages 82 mm of rainfall in Rimouski, about average for rainfall. The wettest on record was 228 mm in 2010.
The hottest September reached 27°C in 1999. The coldest dipped to 0°C in 2000.
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 14.5°C to 17.2°C and overnight lows from 8°C to 9.9°C over the same span.
September is one of the warmer months of the year in Rimouski and about average for rainfall, so plan for around 15.3°C daytime highs and 8.6°C at night.
Not quite — September is the 9th coolest month in Rimouski, averaging 12°C.
For September in Rimouski, pack light layers you can adjust through the day, with typical highs of 15.3°C and lows of 8.6°C. Bring an umbrella or light rain jacket too.
Relative humidity in September averages 82% — quite humid.
Average wind speed in September is 1.9 m/s. The windiest September on record averaged 2.3 m/s (1988).
The wettest September on record was 2010 with 228 mm. On average, September sees 82 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 Rimouski 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.
