September is one of the warmer months of the year in Grand Falls, with average highs near 16.6°C and lows around 6.7°C (mean 11.7°C). It is about average for rainfall, averaging 96 mm of rainfall and 86% relative humidity across the period.
September is one of the warmer months of the year in Grand Falls. Across 45 years of records, the warmest September in Grand Falls was 2012 — when the month averaged 14.1°C — while the coldest was 1986 at 8.4°C. Typical September days reach 16.6°C with nights near 6.7°C. The long-term trend is warming, about 0.4°C per decade.
September is about average for rainfall in Grand Falls, averaging 96 mm of rainfall. The wettest September on record was 2004 with 210 mm, while the driest was 2025 at 48 mm.
Relative humidity in Grand Falls during September averages 86%. The most humid September was 2024 at 88%, and the least humid was 1989 at 77%.
September receives about 3.4 kWh/m²/day of solar energy in Grand Falls. The sunniest September was 2025 at 3.8 kWh/m²/day, and the cloudiest was 1991 at 2.8.
Average wind speed in Grand Falls during September is 0.1 m/s. The windiest Septembers were 2023, 2024 and 2025, among others at 0.1 m/s, while the calmest were 2023, 2024 and 2025, among others at 0.1 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 10.9°C | 11.4°C | 11.7°C | 11.8°C | 12.9°C | +2°C |
| Avg High | 15.8°C | 16.2°C | 16.7°C | 16.7°C | 17.8°C | +2°C |
| Avg Low | 5.9°C | 6.6°C | 6.7°C | 7.0°C | 7.9°C | +2°C |
| Avg Rain | 82 mm | 104 mm | 107 mm | 100 mm | 79 mm | -3 mm |
September temperatures in Grand Falls have risen by about 1.9°C between 1981–1985 and 2021–2025.
September has ranged from a record low of -3.6°C (1986) to a record high of 28.2°C (2001).
Rainfall in September is about average for rainfall, averaging 96 mm, with a wettest year of 210 mm.
One of the best times to visit Grand Falls
September is one of the best times to visit Grand Falls. Expect days averaging 16.6°C and nights around 6.7°C (mean 11.7°C) — warmer than Grand Falls's yearly average — with higher rainfall (96 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 | 17.3°C | 12.3°C | 7.2°C | 25.2°C | 2.7°C | 48 mm | 85% | 0.1 m/s | 3.8 |
| 2024 | 17.7°C | 13.0°C | 8.2°C | 25.0°C | 4.4°C | 69 mm | 88% | 0.1 m/s | 3.4 |
| 2023 | 18.1°C | 13.3°C | 8.4°C | 25.8°C | 1.6°C | 80 mm | 88% | 0.1 m/s | 3.2 |
| 2022 | 17.8°C | 13.3°C | 8.8°C | 26.6°C | 2.5°C | 95 mm | 86% | 0.1 m/s | 3.5 |
| 2021 | 18.5°C | 13.1°C | 7.6°C | 25.1°C | 2.3°C | 121 mm | 87% | 0.1 m/s | 3.4 |
| 2020 | 17.7°C | 12.5°C | 7.4°C | 24.2°C | 0.4°C | 60 mm | 84% | 0.1 m/s | 3.6 |
| 2019 | 14.5°C | 9.8°C | 5.1°C | 22.3°C | 0.4°C | 100 mm | 87% | 0.1 m/s | 3.3 |
| 2018 | 15.8°C | 10.4°C | 5.0°C | 24.3°C | -3.0°C | 84 mm | 85% | 0.1 m/s | 3.7 |
| 2017 | 16.6°C | 12.2°C | 7.7°C | 25.8°C | -0.3°C | 81 mm | 88% | 0.1 m/s | 3.1 |
| 2016 | 15.4°C | 10.8°C | 6.2°C | 26.8°C | 0.7°C | 104 mm | 87% | 0.1 m/s | 3.2 |
| 2015 | 17.5°C | 12.2°C | 7.0°C | 24.5°C | -1.2°C | 77 mm | 87% | 0.1 m/s | 3.2 |
| 2014 | 16.9°C | 11.5°C | 6.2°C | 24.5°C | -1.2°C | 61 mm | 83% | 0.1 m/s | 3.7 |
| 2013 | 17.5°C | 13.0°C | 8.6°C | 23.6°C | -1.6°C | 129 mm | 87% | 0.1 m/s | 3.1 |
| 2012 🔥 | 19.1°C | 14.1°C | 9.1°C | 24.8°C | 3.1°C | 129 mm | 87% | 0.1 m/s | 3.5 |
| 2011 | 17.2°C | 12.3°C | 7.4°C | 24.4°C | 2.1°C | 73 mm | 85% | 0.1 m/s | 3.6 |
| 2010 | 16.5°C | 12.0°C | 7.6°C | 25.9°C | -0.6°C | 161 mm | 86% | 0.1 m/s | 3.1 |
| 2009 | 15.7°C | 10.5°C | 5.4°C | 22.0°C | -2.9°C | 66 mm | 85% | 0.1 m/s | 3.6 |
| 2008 | 17.6°C | 12.5°C | 7.4°C | 26.6°C | -2.2°C | 64 mm | 85% | 0.1 m/s | 3.3 |
| 2007 | 16.1°C | 10.9°C | 5.7°C | 23.6°C | 2.3°C | 115 mm | 85% | 0.1 m/s | 3.2 |
| 2006 | 16.9°C | 11.9°C | 6.8°C | 23.4°C | 3.5°C | 70 mm | 86% | 0.1 m/s | 3.3 |
| 2005 | 16.6°C | 11.8°C | 7.1°C | 25.3°C | 1.3°C | 121 mm | 87% | 0.1 m/s | 3 |
| 2004 🌧️ | 15.4°C | 10.8°C | 6.2°C | 23.7°C | 1.4°C | 210 mm | 86% | 0.1 m/s | 3.2 |
| 2003 | 18.8°C | 13.8°C | 8.7°C | 25.5°C | 3.4°C | 63 mm | 87% | 0.1 m/s | 3.7 |
| 2002 | 16.2°C | 11.1°C | 5.9°C | 23.2°C | -0.5°C | 143 mm | 85% | 0.1 m/s | 3.4 |
| 2001 | 17.2°C | 12.2°C | 7.2°C | 28.2°C | 1.4°C | 119 mm | 87% | 0.1 m/s | 3.5 |
| 2000 | 16.3°C | 11.3°C | 6.3°C | 22.9°C | -1.6°C | 98 mm | 85% | 0.1 m/s | 3.3 |
| 1999 | 19.1°C | 13.7°C | 8.2°C | 25.3°C | 0.9°C | 123 mm | 87% | 0.1 m/s | 3.3 |
| 1998 | 15.5°C | 11.4°C | 7.2°C | 23.1°C | 2.3°C | 139 mm | 88% | 0.1 m/s | 3.2 |
| 1997 | 16.7°C | 12.2°C | 7.8°C | 23.0°C | 0.0°C | 100 mm | 87% | 0.1 m/s | 3 |
| 1996 | 14.1°C | 9.1°C | 4.2°C | 23.5°C | -0.4°C | 125 mm | 86% | 0.1 m/s | 3.3 |
| 1995 | 16.0°C | 10.8°C | 5.7°C | 20.8°C | -0.1°C | 93 mm | 84% | 0.1 m/s | 3.7 |
| 1994 | 15.3°C | 10.6°C | 6.0°C | 20.0°C | 0.8°C | 116 mm | 88% | 0.1 m/s | 3.1 |
| 1993 | 16.9°C | 11.9°C | 6.9°C | 23.8°C | 1.2°C | 69 mm | 85% | 0.1 m/s | 3.4 |
| 1992 | 16.9°C | 11.9°C | 6.8°C | 24.2°C | -0.3°C | 73 mm | 86% | 0.1 m/s | 3.4 |
| 1991 | 14.7°C | 10.4°C | 6.0°C | 22.1°C | 0.3°C | 126 mm | 88% | 0.1 m/s | 2.8 |
| 1990 | 17.3°C | 12.0°C | 6.7°C | 22.9°C | 1.2°C | 75 mm | 83% | 0.1 m/s | 3.5 |
| 1989 | 18.7°C | 12.5°C | 6.3°C | 26.6°C | -1.4°C | 78 mm | 77% | 0.1 m/s | 3.7 |
| 1988 | 15.9°C | 10.8°C | 5.8°C | 22.8°C | -0.3°C | 77 mm | 82% | 0.1 m/s | 3.5 |
| 1987 | 15.5°C | 10.6°C | 5.7°C | 22.4°C | 0.6°C | 55 mm | 82% | 0.1 m/s | 3.1 |
| 1986 ❄️ | 13.2°C | 8.4°C | 3.6°C | 20.6°C | -3.6°C | 83 mm | 86% | 0.1 m/s | 3.5 |
| 1985 | 15.5°C | 10.8°C | 6.0°C | 24.7°C | 0.9°C | 64 mm | 86% | 0.1 m/s | 3.5 |
| 1984 | 14.8°C | 10.0°C | 5.2°C | 23.9°C | -0.8°C | 102 mm | 85% | 0.1 m/s | 3.5 |
| 1983 | 15.8°C | 11.3°C | 6.8°C | 25.2°C | 1.7°C | 71 mm | 87% | 0.1 m/s | — |
| 1982 | 16.1°C | 11.3°C | 6.5°C | 25.3°C | -1.3°C | 110 mm | 87% | 0.1 m/s | — |
| 1981 | 16.7°C | 12.1°C | 7.5°C | 24.9°C | 1.0°C | 94 mm | 86% | 0.1 m/s | — |
Actual recorded September data for each year, 1981–2025 — sourced from NASA POWER.
The average high in September is around 16.6°C with lows near 6.7°C (mean 11.7°C), based on 45 years of NASA POWER data.
September averages 96 mm of rainfall in Grand Falls, about average for rainfall. The wettest on record was 210 mm in 2004.
The hottest September reached 28.2°C in 2001. The coldest dipped to -3.6°C in 1986.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average September temperatures have risen by about 1.9°C. Daytime highs moved from 15.8°C to 17.9°C and overnight lows from 6.4°C to 8°C over the same span.
September is one of the warmer months of the year in Grand Falls and about average for rainfall, so plan for around 16.6°C daytime highs and 6.7°C at night.
Not quite — September is the 9th coolest month in Grand Falls, averaging 11.7°C.
For September in Grand Falls, pack warm layers and a jacket for chilly mornings, with typical highs of 16.6°C and lows of 6.7°C. Bring an umbrella or light rain jacket too.
Relative humidity in September averages 86% — quite humid.
Average wind speed in September is 0.1 m/s. The windiest September on record averaged 0.1 m/s (1981).
The wettest September on record was 2004 with 210 mm. On average, September sees 96 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 Grand Falls 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.
