September is one of the warmer months of the year in Lac-Brome, with average highs near 19.4°C and lows around 9.3°C (mean 14.4°C). It is about average for rainfall, averaging 99 mm of rainfall and 81% relative humidity across the period.
September is one of the warmer months of the year in Lac-Brome. Across 45 years of records, the warmest September in Lac-Brome was 2015 — when the month averaged 17.2°C — while the coldest was 1991 at 11.9°C. Typical September days reach 19.4°C with nights near 9.3°C. The long-term trend is warming, about 0.7°C per decade.
September is about average for rainfall in Lac-Brome, averaging 99 mm of rainfall. The wettest September on record was 1999 with 208 mm, while the driest was 2024 at 52 mm.
Relative humidity in Lac-Brome during September averages 81%. The most humid September was 2010 at 85%, and the least humid was 2020 at 77%.
September receives about 3.9 kWh/m²/day of solar energy in Lac-Brome. 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 Lac-Brome during September is 0.3 m/s. The windiest Septembers were 2023, 2024 and 2025, among others at 0.3 m/s, while the calmest were 1982 and 1987 at 0.2 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 13.3°C | 13.5°C | 14.7°C | 15.2°C | 15.5°C | +2.2°C |
| Avg High | 18.3°C | 18.3°C | 19.8°C | 20.4°C | 20.6°C | +2.3°C |
| Avg Low | 8.2°C | 8.6°C | 9.5°C | 10.1°C | 10.4°C | +2.2°C |
| Avg Rain | 96 mm | 112 mm | 90 mm | 100 mm | 93 mm | -2 mm |
September temperatures in Lac-Brome have risen by about 2.2°C between 1981–1985 and 2021–2025.
September has ranged from a record low of -1.4°C (2014) to a record high of 30.5°C (2002).
Rainfall in September is about average for rainfall, averaging 99 mm, with a wettest year of 208 mm.
Daytime highs and overnight lows have shifted differently — highs rose about 0.8°C per decade while lows rose 0.6°C per decade, widening the gap between day and night.
One of the best times to visit Lac-Brome
September is one of the best times to visit Lac-Brome. Expect days averaging 19.4°C and nights around 9.3°C (mean 14.4°C) — warmer than Lac-Brome's yearly average — with higher rainfall (99 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 | 20.8°C | 15.3°C | 9.7°C | 24.2°C | 2.0°C | 142 mm | 79% | 0.3 m/s | 4.5 |
| 2024 | 21.6°C | 16.4°C | 11.3°C | 26.1°C | 6.3°C | 52 mm | 81% | 0.3 m/s | 4.2 |
| 2023 | 21.5°C | 16.4°C | 11.3°C | 28.9°C | 5.2°C | 82 mm | 82% | 0.3 m/s | 4 |
| 2022 | 19.3°C | 14.6°C | 9.9°C | 26.5°C | 2.2°C | 142 mm | 82% | 0.3 m/s | 3.7 |
| 2021 | 20.7°C | 15.9°C | 11.0°C | 26.2°C | 6.6°C | 80 mm | 78% | 0.3 m/s | 3.7 |
| 2020 | 19.6°C | 14.3°C | 9.0°C | 25.3°C | 0.3°C | 60 mm | 77% | 0.3 m/s | 3.6 |
| 2019 | 19.4°C | 14.1°C | 8.7°C | 26.0°C | 1.7°C | 99 mm | 81% | 0.3 m/s | 3.8 |
| 2018 | 21.4°C | 16.3°C | 11.2°C | 29.0°C | 3.7°C | 95 mm | 80% | 0.3 m/s | 3.9 |
| 2017 | 21.7°C | 16.5°C | 11.4°C | 28.9°C | 4.4°C | 69 mm | 82% | 0.3 m/s | 4.2 |
| 2016 | 21.3°C | 15.9°C | 10.5°C | 26.9°C | 2.7°C | 67 mm | 79% | 0.3 m/s | 4.5 |
| 2015 🔥 | 22.6°C | 17.2°C | 11.7°C | 28.6°C | 2.9°C | 107 mm | 80% | 0.3 m/s | 4.3 |
| 2014 | 19.9°C | 14.4°C | 9.0°C | 27.0°C | -1.4°C | 56 mm | 81% | 0.3 m/s | 3.8 |
| 2013 | 18.3°C | 13.2°C | 8.1°C | 28.8°C | 1.4°C | 124 mm | 83% | 0.3 m/s | 3.8 |
| 2012 | 19.1°C | 13.9°C | 8.8°C | 25.3°C | 3.0°C | 131 mm | 80% | 0.3 m/s | 3.9 |
| 2011 | 20.7°C | 16.0°C | 11.3°C | 27.3°C | 2.8°C | 126 mm | 85% | 0.3 m/s | 3.7 |
| 2010 | 19.2°C | 14.9°C | 10.6°C | 29.2°C | 4.7°C | 129 mm | 85% | 0.3 m/s | 3.3 |
| 2009 | 18.7°C | 13.5°C | 8.3°C | 24.1°C | 1.7°C | 61 mm | 81% | 0.3 m/s | 4.3 |
| 2008 | 19.8°C | 14.8°C | 9.8°C | 27.3°C | 1.3°C | 55 mm | 84% | 0.3 m/s | 3.7 |
| 2007 | 20.0°C | 14.9°C | 9.7°C | 27.7°C | 3.9°C | 86 mm | 81% | 0.3 m/s | 4.4 |
| 2006 | 18.7°C | 13.6°C | 8.5°C | 23.5°C | 3.3°C | 80 mm | 84% | 0.3 m/s | 3.4 |
| 2005 | 20.7°C | 15.8°C | 10.8°C | 27.1°C | 3.3°C | 119 mm | 83% | 0.3 m/s | 4 |
| 2004 | 20.0°C | 14.7°C | 9.4°C | 24.3°C | 4.0°C | 81 mm | 82% | 0.3 m/s | 4.2 |
| 2003 | 20.6°C | 15.4°C | 10.2°C | 26.8°C | 5.0°C | 83 mm | 82% | 0.3 m/s | 4 |
| 2002 | 21.3°C | 15.9°C | 10.6°C | 30.5°C | 2.9°C | 152 mm | 79% | 0.3 m/s | 4.2 |
| 2001 | 19.9°C | 14.9°C | 9.8°C | 27.7°C | 1.7°C | 75 mm | 79% | 0.3 m/s | 4.1 |
| 2000 | 18.2°C | 13.2°C | 8.2°C | 27.5°C | -0.3°C | 106 mm | 80% | 0.3 m/s | 3.7 |
| 1999 🌧️ | 21.1°C | 16.2°C | 11.4°C | 29.4°C | 4.1°C | 208 mm | 81% | 0.3 m/s | 3.6 |
| 1998 | 19.4°C | 14.5°C | 9.6°C | 25.4°C | 2.0°C | 118 mm | 83% | 0.3 m/s | 3.8 |
| 1997 | 18.2°C | 13.3°C | 8.3°C | 24.4°C | 1.1°C | 71 mm | 83% | 0.3 m/s | 3.3 |
| 1996 | 19.2°C | 14.8°C | 10.3°C | 27.6°C | 2.3°C | 78 mm | 83% | 0.3 m/s | 3.7 |
| 1995 | 17.5°C | 12.0°C | 6.4°C | 24.2°C | 0.8°C | 96 mm | 78% | 0.3 m/s | 4 |
| 1994 | 17.6°C | 13.2°C | 8.8°C | 22.7°C | 4.7°C | 92 mm | 84% | 0.3 m/s | 3.6 |
| 1993 | 17.5°C | 12.7°C | 7.8°C | 25.6°C | -0.4°C | 124 mm | 81% | 0.3 m/s | 3.5 |
| 1992 | 18.4°C | 13.4°C | 8.4°C | 25.7°C | -1.1°C | 106 mm | 81% | 0.3 m/s | 3.6 |
| 1991 ❄️ | 16.8°C | 11.9°C | 7.0°C | 25.4°C | -0.6°C | 134 mm | 80% | 0.3 m/s | 3.8 |
| 1990 | 17.5°C | 12.6°C | 7.8°C | 23.4°C | 1.5°C | 93 mm | 84% | 0.3 m/s | 3.2 |
| 1989 | 18.9°C | 13.8°C | 8.7°C | 28.1°C | -0.1°C | 128 mm | 81% | 0.3 m/s | 3.7 |
| 1988 | 18.0°C | 12.6°C | 7.2°C | 25.1°C | 0.7°C | 65 mm | 79% | 0.3 m/s | 3.8 |
| 1987 | 17.8°C | 13.1°C | 8.4°C | 26.2°C | 0.0°C | 116 mm | 83% | 0.2 m/s | 3.6 |
| 1986 | 17.1°C | 12.2°C | 7.2°C | 22.1°C | 0.9°C | 120 mm | 83% | 0.3 m/s | 3.4 |
| 1985 | 19.2°C | 14.1°C | 9.1°C | 25.2°C | 2.1°C | 83 mm | 81% | 0.3 m/s | 4 |
| 1984 | 17.3°C | 12.1°C | 7.0°C | 23.8°C | -0.1°C | 59 mm | 79% | 0.3 m/s | 4.2 |
| 1983 | 20.1°C | 14.8°C | 9.5°C | 27.4°C | 2.7°C | 66 mm | 77% | 0.3 m/s | — |
| 1982 | 18.7°C | 13.8°C | 8.8°C | 24.9°C | 4.1°C | 85 mm | 83% | 0.2 m/s | — |
| 1981 | 17.4°C | 12.8°C | 8.2°C | 24.7°C | 0.3°C | 135 mm | 83% | 0.3 m/s | — |
Actual recorded September data for each year, 1981–2025 — sourced from NASA POWER.
The average high in September is around 19.4°C with lows near 9.3°C (mean 14.4°C), based on 45 years of NASA POWER data.
September averages 99 mm of rainfall in Lac-Brome, about average for rainfall. The wettest on record was 208 mm in 1999.
The hottest September reached 30.5°C in 2002. The coldest dipped to -1.4°C in 2014.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average September temperatures have risen by about 2.2°C. Daytime highs moved from 18.5°C to 20.8°C and overnight lows from 8.5°C to 10.6°C over the same span.
September is one of the warmer months of the year in Lac-Brome and about average for rainfall, so plan for around 19.4°C daytime highs and 9.3°C at night.
Not quite — September is the 9th coolest month in Lac-Brome, averaging 14.4°C.
For September in Lac-Brome, pack light layers you can adjust through the day, with typical highs of 19.4°C and lows of 9.3°C. Bring an umbrella or light rain jacket too.
Relative humidity in September averages 81% — quite humid.
Average wind speed in September is 0.3 m/s. The windiest September on record averaged 0.3 m/s (1981).
The wettest September on record was 1999 with 208 mm. On average, September sees 99 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 Lac-Brome 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.
