September is one of the warmer months of the year in Fort St. John, with average highs near 15.7°C and lows around 4.4°C (mean 10.1°C). It is about average for rainfall, averaging 47 mm of rainfall and 73% relative humidity across the period.
September is one of the warmer months of the year in Fort St. John. Across 45 years of records, the warmest September in Fort St. John was 2025 — when the month averaged 14.3°C — while the coldest was 2018 at 4.4°C. Typical September days reach 15.7°C with nights near 4.4°C. The long-term trend is warming, about 0.5°C per decade.
September is about average for rainfall in Fort St. John, averaging 47 mm of rainfall. The wettest September on record was 1985 with 116 mm, while the driest was 1990 at 9 mm.
Relative humidity in Fort St. John during September averages 73%. The most humid September was 2019 at 83%, and the least humid was 2012 at 58%.
September receives about 3.3 kWh/m²/day of solar energy in Fort St. John. The sunniest September was 2012 at 3.9 kWh/m²/day, and the cloudiest were 2004 and 2019 at 2.8.
Average wind speed in Fort St. John during September is 0.5 m/s. The windiest Septembers were 2004, 2009 and 2012 at 0.6 m/s, while the calmest were 1984 and 1996 at 0.4 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 9.0°C | 10.2°C | 9.8°C | 10.0°C | 12.1°C | +3.1°C |
| Avg High | 14.6°C | 15.9°C | 15.2°C | 15.6°C | 17.8°C | +3.2°C |
| Avg Low | 3.4°C | 4.3°C | 4.3°C | 4.3°C | 6.3°C | +2.9°C |
| Avg Rain | 53 mm | 43 mm | 51 mm | 48 mm | 40 mm | -13 mm |
September temperatures in Fort St. John have risen by about 4.1°C between 1981–1985 and 2021–2025.
September has ranged from a record low of -6.4°C (2018) to a record high of 30.8°C (2006).
Rainfall in September is about average for rainfall, averaging 47 mm, with a wettest year of 116 mm.
One of the best times to visit Fort St. John
September is one of the best times to visit Fort St. John. Expect days averaging 15.7°C and nights around 4.4°C (mean 10.1°C) — warmer than Fort St. John's yearly average — with moderate rainfall (47 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 🔥 | 20.2°C | 14.3°C | 8.4°C | 29.0°C | 0.7°C | 24 mm | 67% | 0.5 m/s | 3.4 |
| 2024 | 17.6°C | 12.0°C | 6.4°C | 28.9°C | -0.3°C | 55 mm | 71% | 0.5 m/s | 3.2 |
| 2023 | 18.1°C | 12.1°C | 6.0°C | 26.3°C | 2.8°C | 29 mm | 66% | 0.5 m/s | 3.4 |
| 2022 | 19.5°C | 13.0°C | 6.6°C | 28.8°C | 0.9°C | 34 mm | 67% | 0.5 m/s | 3.7 |
| 2021 | 16.2°C | 10.9°C | 5.5°C | 23.5°C | 0.4°C | 49 mm | 71% | 0.5 m/s | 3.2 |
| 2020 | 15.1°C | 10.1°C | 5.1°C | 22.9°C | -1.1°C | 48 mm | 81% | 0.5 m/s | 3.2 |
| 2019 | 13.7°C | 9.2°C | 4.6°C | 23.0°C | -5.6°C | 59 mm | 83% | 0.5 m/s | 2.8 |
| 2018 ❄️ | 9.4°C | 4.4°C | -0.6°C | 18.9°C | -6.4°C | 63 mm | 79% | 0.5 m/s | 2.9 |
| 2017 | 18.2°C | 11.9°C | 5.7°C | 29.8°C | -0.5°C | 57 mm | 71% | 0.5 m/s | 3.5 |
| 2016 | 13.8°C | 9.0°C | 4.2°C | 19.8°C | -1.1°C | 95 mm | 81% | 0.5 m/s | 3.2 |
| 2015 | 14.6°C | 8.9°C | 3.3°C | 22.2°C | -0.9°C | 51 mm | 73% | 0.5 m/s | 3.4 |
| 2014 | 16.8°C | 10.5°C | 4.2°C | 27.1°C | -5.4°C | 41 mm | 71% | 0.5 m/s | 2.9 |
| 2013 | 19.2°C | 12.9°C | 6.5°C | 30.1°C | -0.6°C | 27 mm | 70% | 0.5 m/s | 3.7 |
| 2012 | 20.2°C | 13.3°C | 6.4°C | 27.5°C | 2.9°C | 12 mm | 58% | 0.6 m/s | 3.9 |
| 2011 | 16.5°C | 11.1°C | 5.8°C | 24.4°C | 1.5°C | 39 mm | 77% | 0.5 m/s | 3.3 |
| 2010 | 13.9°C | 8.3°C | 2.6°C | 24.0°C | -4.3°C | 32 mm | 71% | 0.5 m/s | 3 |
| 2009 | 18.0°C | 12.4°C | 6.7°C | 27.2°C | -4.0°C | 67 mm | 72% | 0.6 m/s | 3.1 |
| 2008 | 16.5°C | 10.6°C | 4.8°C | 24.6°C | -2.6°C | 28 mm | 72% | 0.5 m/s | 3.2 |
| 2007 | 14.2°C | 8.7°C | 3.2°C | 22.3°C | -4.6°C | 28 mm | 77% | 0.5 m/s | 3.3 |
| 2006 | 17.7°C | 11.8°C | 5.9°C | 30.8°C | -0.8°C | 34 mm | 64% | 0.5 m/s | 3.2 |
| 2005 | 14.4°C | 9.1°C | 3.8°C | 20.0°C | -0.8°C | 44 mm | 73% | 0.5 m/s | 3.2 |
| 2004 | 11.7°C | 7.1°C | 2.6°C | 20.3°C | -4.2°C | 97 mm | 81% | 0.6 m/s | 2.8 |
| 2003 | 15.2°C | 9.5°C | 3.8°C | 24.7°C | -4.9°C | 36 mm | 72% | 0.5 m/s | 3.3 |
| 2002 | 13.8°C | 8.5°C | 3.3°C | 20.9°C | -2.4°C | 68 mm | 75% | 0.5 m/s | 3 |
| 2001 | 17.0°C | 11.0°C | 4.9°C | 24.7°C | -0.1°C | 33 mm | 70% | 0.5 m/s | 3.5 |
| 2000 | 13.9°C | 8.8°C | 3.8°C | 19.2°C | -4.6°C | 74 mm | 81% | 0.5 m/s | 3 |
| 1999 | 16.1°C | 10.2°C | 4.2°C | 24.7°C | -3.1°C | 41 mm | 69% | 0.5 m/s | 3.4 |
| 1998 | 17.6°C | 11.1°C | 4.6°C | 23.7°C | -0.1°C | 17 mm | 60% | 0.5 m/s | 3.7 |
| 1997 | 15.3°C | 10.4°C | 5.4°C | 23.2°C | -0.6°C | 68 mm | 83% | 0.5 m/s | 3.1 |
| 1996 | 12.8°C | 7.7°C | 2.5°C | 21.7°C | -4.3°C | 71 mm | 82% | 0.4 m/s | 2.9 |
| 1995 | 19.3°C | 12.5°C | 5.7°C | 25.8°C | -3.0°C | 16 mm | 66% | 0.5 m/s | 3.7 |
| 1994 | 16.5°C | 11.1°C | 5.6°C | 22.7°C | -2.9°C | 58 mm | 71% | 0.5 m/s | 3.1 |
| 1993 | 15.8°C | 10.0°C | 4.2°C | 23.2°C | -3.9°C | 32 mm | 75% | 0.5 m/s | 3.7 |
| 1992 | 10.8°C | 5.6°C | 0.5°C | 17.6°C | -5.8°C | 95 mm | 75% | 0.5 m/s | 2.9 |
| 1991 | 16.7°C | 11.0°C | 5.3°C | 24.1°C | 0.4°C | 27 mm | 71% | 0.5 m/s | 3.1 |
| 1990 | 18.6°C | 11.9°C | 5.2°C | 25.5°C | -1.4°C | 9 mm | 64% | 0.5 m/s | 3.7 |
| 1989 | 16.2°C | 10.4°C | 4.5°C | 24.9°C | -2.0°C | 71 mm | 76% | 0.5 m/s | 3.2 |
| 1988 | 15.6°C | 9.7°C | 3.7°C | 30.7°C | -3.3°C | 28 mm | 69% | 0.5 m/s | 3.2 |
| 1987 | 16.9°C | 11.4°C | 6.0°C | 22.8°C | 1.2°C | 14 mm | 78% | 0.5 m/s | 3.5 |
| 1986 | 13.2°C | 7.7°C | 2.1°C | 22.4°C | -4.0°C | 85 mm | 74% | 0.5 m/s | 3.1 |
| 1985 🌧️ | 11.9°C | 6.7°C | 1.5°C | 22.7°C | -4.2°C | 116 mm | 77% | 0.5 m/s | 3.1 |
| 1984 | 11.2°C | 6.1°C | 0.9°C | 16.7°C | -5.0°C | 68 mm | 79% | 0.4 m/s | 2.9 |
| 1983 | 12.6°C | 7.4°C | 2.2°C | 19.3°C | -6.0°C | 41 mm | 74% | 0.5 m/s | — |
| 1982 | 16.5°C | 10.8°C | 5.2°C | 25.4°C | -2.6°C | 23 mm | 76% | 0.5 m/s | — |
| 1981 | 17.2°C | 11.0°C | 4.7°C | 29.6°C | -2.3°C | 28 mm | 68% | 0.5 m/s | — |
Actual recorded September data for each year, 1981–2025 — sourced from NASA POWER.
The average high in September is around 15.7°C with lows near 4.4°C (mean 10.1°C), based on 45 years of NASA POWER data.
September averages 47 mm of rainfall in Fort St. John, about average for rainfall. The wettest on record was 116 mm in 1985.
The hottest September reached 30.8°C in 2006. The coldest dipped to -6.4°C in 2018.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average September temperatures have risen by about 4.1°C. Daytime highs moved from 13.9°C to 18.3°C and overnight lows from 2.9°C to 6.6°C over the same span.
September is one of the warmer months of the year in Fort St. John and about average for rainfall, so plan for around 15.7°C daytime highs and 4.4°C at night.
Not quite — September is the 9th coolest month in Fort St. John, averaging 10.1°C.
For September in Fort St. John, pack warm layers and a jacket for chilly mornings, with typical highs of 15.7°C and lows of 4.4°C.
Relative humidity in September averages 73% — moderately humid.
Average wind speed in September is 0.5 m/s. The windiest September on record averaged 0.6 m/s (2004).
The wettest September on record was 1985 with 116 mm. On average, September sees 47 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 Fort St. John 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.
