September is one of the warmer months of the year in Bangor, with average highs near 15.8°C and lows around 12.6°C (mean 14.2°C). It is about average for rainfall, averaging 101 mm of rainfall and 84% relative humidity across the period.
September is one of the warmer months of the year in Bangor. Across 45 years of records, the warmest September in Bangor was 2023 — when the month averaged 16.5°C — while the coldest was 1986 at 12°C. Typical September days reach 15.8°C with nights near 12.6°C. The long-term trend is warming, about 0.3°C per decade.
September is about average for rainfall in Bangor, averaging 101 mm of rainfall. The wettest September on record was 2025 with 220 mm, while the driest was 1986 at 13 mm.
Relative humidity in Bangor during September averages 84%. The most humid September was 1985 at 87%, and the least humid was 1991 at 80%.
September receives about 3 kWh/m²/day of solar energy in Bangor. The sunniest Septembers were 1986, 1991 and 2015 at 3.4 kWh/m²/day, and the cloudiest was 2000 at 2.6.
Average wind speed in Bangor during September is 4.9 m/s. The windiest September was 2011 at 6.2 m/s, while the calmest was 2014 at 3 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 13.6°C | 13.9°C | 14.5°C | 14.2°C | 15.1°C | +1.5°C |
| Avg High | 15.2°C | 15.6°C | 16.1°C | 15.8°C | 16.8°C | +1.6°C |
| Avg Low | 12.1°C | 12.2°C | 12.9°C | 12.6°C | 13.4°C | +1.3°C |
| Avg Rain | 86 mm | 85 mm | 100 mm | 111 mm | 133 mm | +47 mm |
September temperatures in Bangor have risen by about 1.3°C between 1981–1985 and 2021–2025.
September has ranged from a record low of 7.8°C (1982) to a record high of 24.4°C (2021).
Rainfall in September is about average for rainfall, averaging 101 mm, with a wettest year of 220 mm.
One of the best times to visit Bangor
September is one of the best times to visit Bangor. Expect days averaging 15.8°C and nights around 12.6°C (mean 14.2°C) — warmer than Bangor's yearly average — with higher rainfall (101 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 🌧️ | 16.1°C | 14.6°C | 13.0°C | 19.2°C | 10.0°C | 220 mm | 82% | 5.5 m/s | 2.9 |
| 2024 | 16.0°C | 14.1°C | 12.2°C | 21.3°C | 9.8°C | 90 mm | 85% | 4.8 m/s | 2.9 |
| 2023 🔥 | 18.2°C | 16.5°C | 14.8°C | 24.1°C | 11.0°C | 173 mm | 85% | 4.7 m/s | 2.9 |
| 2022 | 16.8°C | 15.2°C | 13.7°C | 20.4°C | 11.4°C | 114 mm | 82% | 4.8 m/s | 3.1 |
| 2021 | 17.6°C | 15.9°C | 14.3°C | 24.4°C | 10.5°C | 98 mm | 85% | 3.6 m/s | 2.9 |
| 2020 | 16.0°C | 14.3°C | 12.6°C | 20.3°C | 9.1°C | 102 mm | 84% | 4.8 m/s | 3.1 |
| 2019 | 16.2°C | 14.6°C | 13.0°C | 20.2°C | 11.6°C | 156 mm | 84% | 5 m/s | 3.1 |
| 2018 | 15.4°C | 13.8°C | 12.2°C | 18.7°C | 9.2°C | 121 mm | 82% | 5.5 m/s | 3.1 |
| 2017 | 15.3°C | 14.0°C | 12.6°C | 17.5°C | 10.7°C | 167 mm | 85% | 5.4 m/s | 2.9 |
| 2016 | 16.8°C | 15.3°C | 13.8°C | 22.8°C | 11.6°C | 109 mm | 86% | 5.3 m/s | 2.9 |
| 2015 | 15.1°C | 13.2°C | 11.3°C | 18.1°C | 10.0°C | 59 mm | 83% | 4.2 m/s | 3.4 |
| 2014 | 17.2°C | 15.3°C | 13.3°C | 20.1°C | 11.7°C | 15 mm | 83% | 3 m/s | 3.3 |
| 2013 | 15.6°C | 13.8°C | 12.0°C | 18.9°C | 9.7°C | 70 mm | 85% | 4.5 m/s | 2.7 |
| 2012 | 14.6°C | 13.1°C | 11.6°C | 17.2°C | 8.7°C | 140 mm | 85% | 5.5 m/s | 3 |
| 2011 | 16.0°C | 14.6°C | 13.1°C | 20.4°C | 11.6°C | 122 mm | 86% | 6.2 m/s | 2.8 |
| 2010 | 15.8°C | 14.2°C | 12.7°C | 20.1°C | 9.3°C | 148 mm | 85% | 5 m/s | 2.9 |
| 2009 | 15.6°C | 14.1°C | 12.5°C | 17.8°C | 9.6°C | 62 mm | 85% | 4.6 m/s | 3 |
| 2008 | 15.5°C | 14.0°C | 12.5°C | 17.1°C | 10.7°C | 133 mm | 86% | 4.5 m/s | 2.9 |
| 2007 | 15.6°C | 14.1°C | 12.7°C | 18.2°C | 8.4°C | 101 mm | 86% | 4.9 m/s | 2.9 |
| 2006 | 17.5°C | 15.8°C | 14.1°C | 20.4°C | 11.7°C | 90 mm | 87% | 5.1 m/s | 3.1 |
| 2005 | 16.7°C | 15.0°C | 13.3°C | 21.4°C | 10.1°C | 100 mm | 85% | 4.9 m/s | 2.9 |
| 2004 | 16.2°C | 14.6°C | 12.9°C | 20.9°C | 11.0°C | 128 mm | 86% | 6 m/s | 3.1 |
| 2003 | 16.2°C | 14.6°C | 13.0°C | 19.7°C | 9.2°C | 117 mm | 84% | 3.9 m/s | 3.1 |
| 2002 | 16.5°C | 14.6°C | 12.7°C | 19.5°C | 10.7°C | 39 mm | 83% | 3.4 m/s | 3.2 |
| 2001 | 15.2°C | 13.7°C | 12.2°C | 18.3°C | 9.7°C | 77 mm | 86% | 5.2 m/s | 2.9 |
| 2000 | 16.3°C | 14.8°C | 13.2°C | 20.4°C | 9.8°C | 154 mm | 86% | 4.7 m/s | 2.6 |
| 1999 | 16.8°C | 15.1°C | 13.4°C | 22.2°C | 11.5°C | 149 mm | 85% | 4.8 m/s | 2.9 |
| 1998 | 16.3°C | 14.6°C | 12.9°C | 20.1°C | 10.3°C | 107 mm | 87% | 4.9 m/s | 3.2 |
| 1997 | 16.1°C | 14.4°C | 12.7°C | 18.4°C | 10.0°C | 55 mm | 84% | 5 m/s | 3.1 |
| 1996 | 16.0°C | 14.0°C | 12.0°C | 19.7°C | 9.6°C | 38 mm | 82% | 4.6 m/s | 3.3 |
| 1995 | 15.4°C | 13.9°C | 12.4°C | 19.1°C | 9.6°C | 88 mm | 83% | 4.5 m/s | 3.3 |
| 1994 | 14.2°C | 12.9°C | 11.5°C | 16.7°C | 9.7°C | 113 mm | 85% | 5.1 m/s | 3 |
| 1993 | 14.7°C | 13.0°C | 11.4°C | 17.9°C | 9.5°C | 83 mm | 83% | 4.8 m/s | 2.8 |
| 1992 | 14.8°C | 13.2°C | 11.6°C | 18.9°C | 9.1°C | 91 mm | 84% | 5.4 m/s | 2.9 |
| 1991 | 17.1°C | 15.0°C | 12.8°C | 21.9°C | 9.2°C | 54 mm | 80% | 4.7 m/s | 3.4 |
| 1990 | 15.0°C | 13.3°C | 11.7°C | 17.9°C | 9.6°C | 73 mm | 80% | 4.9 m/s | 3 |
| 1989 | 15.8°C | 14.2°C | 12.6°C | 17.8°C | 10.7°C | 32 mm | 84% | 4.7 m/s | 2.7 |
| 1988 | 14.3°C | 13.0°C | 11.8°C | 20.7°C | 8.2°C | 86 mm | 84% | 5.6 m/s | 2.7 |
| 1987 | 15.1°C | 13.5°C | 12.0°C | 18.1°C | 8.8°C | 100 mm | 84% | 5.1 m/s | 3 |
| 1986 ❄️ | 13.6°C | 12.0°C | 10.4°C | 15.6°C | 8.2°C | 13 mm | 81% | 3.8 m/s | 3.4 |
| 1985 | 15.8°C | 14.2°C | 12.7°C | 19.5°C | 10.2°C | 61 mm | 87% | 5 m/s | 2.8 |
| 1984 | 14.9°C | 13.5°C | 12.2°C | 18.9°C | 9.6°C | 130 mm | 82% | 5.4 m/s | 2.9 |
| 1983 | 15.2°C | 13.7°C | 12.1°C | 18.3°C | 10.3°C | 116 mm | 84% | 5.9 m/s | — |
| 1982 | 15.7°C | 13.9°C | 12.1°C | 21.1°C | 7.8°C | 97 mm | 85% | 4.8 m/s | — |
| 1981 | 16.4°C | 14.8°C | 13.2°C | 19.2°C | 11.2°C | 137 mm | 82% | 5.3 m/s | — |
Actual recorded September data for each year, 1981–2025 — sourced from NASA POWER.
The average high in September is around 15.8°C with lows near 12.6°C (mean 14.2°C), based on 45 years of NASA POWER data.
September averages 101 mm of rainfall in Bangor, about average for rainfall. The wettest on record was 220 mm in 2025.
The hottest September reached 24.4°C in 2021. The coldest dipped to 7.8°C in 1982.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average September temperatures have risen by about 1.3°C. Daytime highs moved from 15.6°C to 16.9°C and overnight lows from 12.5°C to 13.6°C over the same span.
September is one of the warmer months of the year in Bangor and about average for rainfall, so plan for around 15.8°C daytime highs and 12.6°C at night.
Not quite — September is the 10th coolest month in Bangor, averaging 14.2°C.
For September in Bangor, pack light layers you can adjust through the day, with typical highs of 15.8°C and lows of 12.6°C. Bring an umbrella or light rain jacket too.
Relative humidity in September averages 84% — quite humid.
Average wind speed in September is 4.9 m/s. The windiest September on record averaged 6.2 m/s (2011).
The wettest September on record was 2025 with 220 mm. On average, September sees 101 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 Bangor 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.
