September is one of the warmer months of the year in Chatham, with average highs near 22.6°C and lows around 13.7°C (mean 18.2°C). It is a relatively wet time of year, averaging 69 mm of rainfall and 74% relative humidity across the period.
September is one of the warmer months of the year in Chatham. Across 45 years of records, the warmest September in Chatham was 2016 — when the month averaged 21.3°C — while the coldest was 1984 at 14.6°C. Typical September days reach 22.6°C with nights near 13.7°C. The long-term trend is warming, about 1°C per decade.
September is a relatively wet time of year in Chatham, averaging 69 mm of rainfall. The wettest September on record was 1986 with 181 mm, while the driest was 1995 at 17 mm.
Relative humidity in Chatham during September averages 74%. The most humid Septembers were 1986 and 1987 at 82%, and the least humid was 2025 at 64%.
September receives about 4.2 kWh/m²/day of solar energy in Chatham. The sunniest Septembers were 1999, 2004 and 2025 at 4.8 kWh/m²/day, and the cloudiest was 1993 at 3.2.
Average wind speed in Chatham during September is 3.2 m/s. The windiest September was 2010 at 3.9 m/s, while the calmest was 2025 at 2.3 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 16.3°C | 17.3°C | 18.6°C | 19.2°C | 19.9°C | +3.6°C |
| Avg High | 20.6°C | 21.9°C | 23.1°C | 23.3°C | 24.5°C | +3.9°C |
| Avg Low | 12.0°C | 12.7°C | 14.1°C | 15.0°C | 15.3°C | +3.3°C |
| Avg Rain | 102 mm | 56 mm | 71 mm | 72 mm | 31 mm | -71 mm |
September temperatures in Chatham have risen by about 4.2°C between 1981–1985 and 2021–2025.
September has ranged from a record low of 2°C (1993) to a record high of 32.5°C (2002).
Rainfall in September is a relatively wet time of year, averaging 69 mm, with a wettest year of 181 mm.
One of the best times to visit Chatham
September is one of the best times to visit Chatham. Expect days averaging 22.6°C and nights around 13.7°C (mean 18.2°C) — warmer than Chatham's yearly average — with moderate rainfall (69 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 | 25.8°C | 20.6°C | 15.3°C | 30.0°C | 10.0°C | 20 mm | 64% | 2.3 m/s | 4.8 |
| 2024 | 25.3°C | 20.8°C | 16.3°C | 29.4°C | 9.4°C | 31 mm | 71% | 3 m/s | 4.4 |
| 2023 | 24.0°C | 19.7°C | 15.4°C | 31.0°C | 11.0°C | 32 mm | 71% | 2.7 m/s | 4 |
| 2022 | 24.1°C | 19.8°C | 15.5°C | 30.7°C | 9.3°C | 30 mm | 69% | 3.2 m/s | 4.1 |
| 2021 | 24.6°C | 19.9°C | 15.3°C | 29.3°C | 9.3°C | 50 mm | 69% | 3.8 m/s | 4.4 |
| 2020 | 23.4°C | 18.8°C | 14.2°C | 28.3°C | 6.7°C | 21 mm | 71% | 3.7 m/s | 4.3 |
| 2019 | 23.8°C | 19.8°C | 15.8°C | 28.0°C | 11.6°C | 108 mm | 79% | 3.2 m/s | 4 |
| 2018 | 24.1°C | 20.3°C | 16.4°C | 31.0°C | 8.1°C | 85 mm | 79% | 3.3 m/s | 3.8 |
| 2017 | 23.6°C | 19.4°C | 15.1°C | 31.3°C | 7.8°C | 62 mm | 76% | 2.7 m/s | 4.5 |
| 2016 🔥 | 25.6°C | 21.3°C | 17.1°C | 31.5°C | 13.4°C | 38 mm | 70% | 3.2 m/s | 4.4 |
| 2015 | 24.7°C | 20.6°C | 16.5°C | 30.3°C | 10.4°C | 77 mm | 75% | 3 m/s | 4.5 |
| 2014 | 22.0°C | 17.8°C | 13.6°C | 29.4°C | 8.2°C | 82 mm | 76% | 3.1 m/s | 4.3 |
| 2013 | 22.2°C | 18.0°C | 13.7°C | 31.4°C | 8.0°C | 60 mm | 74% | 3.1 m/s | 4.4 |
| 2012 | 22.0°C | 17.9°C | 13.8°C | 29.1°C | 6.0°C | 80 mm | 72% | 3.2 m/s | 4.4 |
| 2011 | 21.9°C | 18.1°C | 14.2°C | 31.6°C | 7.7°C | 79 mm | 78% | 3.4 m/s | 3.6 |
| 2010 | 22.8°C | 18.3°C | 13.8°C | 31.0°C | 10.0°C | 50 mm | 69% | 3.9 m/s | 4 |
| 2009 | 23.3°C | 19.0°C | 14.7°C | 26.4°C | 7.2°C | 36 mm | 72% | 3.1 m/s | 4.5 |
| 2008 | 23.7°C | 19.2°C | 14.8°C | 31.9°C | 11.1°C | 82 mm | 73% | 3.1 m/s | 4.3 |
| 2007 | 24.3°C | 19.7°C | 15.1°C | 30.6°C | 8.1°C | 43 mm | 70% | 3 m/s | 4.6 |
| 2006 | 21.0°C | 17.0°C | 13.0°C | 26.7°C | 6.7°C | 84 mm | 77% | 3.7 m/s | 3.5 |
| 2005 | 25.1°C | 20.4°C | 15.7°C | 30.0°C | 9.4°C | 69 mm | 71% | 3.3 m/s | 4.5 |
| 2004 | 24.3°C | 19.7°C | 15.1°C | 27.7°C | 9.4°C | 26 mm | 73% | 3.1 m/s | 4.8 |
| 2003 | 21.2°C | 16.9°C | 12.7°C | 26.7°C | 5.5°C | 128 mm | 75% | 3.3 m/s | 4.5 |
| 2002 | 25.2°C | 20.2°C | 15.2°C | 32.5°C | 8.3°C | 71 mm | 69% | 3 m/s | 4.7 |
| 2001 | 21.1°C | 16.5°C | 11.9°C | 27.5°C | 4.9°C | 78 mm | 73% | 3.3 m/s | 4.3 |
| 2000 | 21.3°C | 17.3°C | 13.2°C | 29.6°C | 5.8°C | 98 mm | 76% | 3.8 m/s | 4 |
| 1999 | 23.4°C | 18.4°C | 13.5°C | 29.8°C | 6.0°C | 79 mm | 67% | 3.2 m/s | 4.8 |
| 1998 | 25.1°C | 20.3°C | 15.6°C | 31.0°C | 10.8°C | 30 mm | 68% | 3.2 m/s | 4.6 |
| 1997 | 22.5°C | 18.0°C | 13.4°C | 26.9°C | 7.1°C | 32 mm | 72% | 3.5 m/s | 4.1 |
| 1996 | 21.5°C | 17.4°C | 13.2°C | 29.5°C | 7.3°C | 102 mm | 76% | 3.4 m/s | 3.8 |
| 1995 | 21.4°C | 16.5°C | 11.5°C | 29.0°C | 3.5°C | 17 mm | 66% | 3.2 m/s | 4.4 |
| 1994 | 22.3°C | 17.2°C | 12.1°C | 28.3°C | 6.5°C | 26 mm | 71% | 3.2 m/s | 4.4 |
| 1993 | 19.2°C | 15.1°C | 10.9°C | 26.9°C | 2.0°C | 77 mm | 74% | 3.4 m/s | 3.2 |
| 1992 | 20.3°C | 16.1°C | 11.9°C | 25.4°C | 4.5°C | 88 mm | 77% | 3.5 m/s | 4.2 |
| 1991 | 22.0°C | 17.1°C | 12.2°C | 30.2°C | 3.1°C | 21 mm | 66% | 3.2 m/s | 4.2 |
| 1990 | 21.5°C | 16.8°C | 12.2°C | 28.5°C | 4.6°C | 90 mm | 76% | 3.3 m/s | 4.1 |
| 1989 | 20.4°C | 16.1°C | 11.8°C | 26.3°C | 2.2°C | 95 mm | 78% | 3 m/s | 4.1 |
| 1988 | 21.9°C | 17.3°C | 12.8°C | 26.7°C | 7.7°C | 55 mm | 73% | 3.5 m/s | 4.1 |
| 1987 | 20.4°C | 16.7°C | 12.9°C | 24.9°C | 6.5°C | 85 mm | 82% | 2.6 m/s | 4.1 |
| 1986 🌧️ | 21.0°C | 16.6°C | 12.2°C | 25.5°C | 5.7°C | 181 mm | 82% | 3.1 m/s | 3.9 |
| 1985 | 20.9°C | 16.6°C | 12.2°C | 28.1°C | 4.5°C | 63 mm | 79% | 3 m/s | 4.1 |
| 1984 ❄️ | 18.7°C | 14.6°C | 10.5°C | 26.8°C | 5.2°C | 108 mm | 79% | 2.9 m/s | 3.9 |
| 1983 | 21.7°C | 17.0°C | 12.2°C | 28.8°C | 4.0°C | 82 mm | 73% | 3.1 m/s | — |
| 1982 | 20.5°C | 16.1°C | 11.7°C | 27.4°C | 4.7°C | 98 mm | 78% | 2.7 m/s | — |
| 1981 | 19.7°C | 15.9°C | 12.0°C | 25.9°C | 5.4°C | 149 mm | 80% | 3.4 m/s | — |
Actual recorded September data for each year, 1981–2025 — sourced from NASA POWER.
The average high in September is around 22.6°C with lows near 13.7°C (mean 18.2°C), based on 45 years of NASA POWER data.
September averages 69 mm of rainfall in Chatham, a relatively wet time of year. The wettest on record was 181 mm in 1986.
The hottest September reached 32.5°C in 2002. The coldest dipped to 2°C in 1993.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average September temperatures have risen by about 4.2°C. Daytime highs moved from 20.3°C to 24.8°C and overnight lows from 11.7°C to 15.6°C over the same span.
September is one of the warmer months of the year in Chatham and a relatively wet time of year, so plan for around 22.6°C daytime highs and 13.7°C at night.
Not quite — September is the 9th coolest month in Chatham, averaging 18.2°C.
For September in Chatham, pack light layers you can adjust through the day, with typical highs of 22.6°C and lows of 13.7°C. Bring an umbrella or light rain jacket too.
Relative humidity in September averages 74% — moderately humid.
Average wind speed in September is 3.2 m/s. The windiest September on record averaged 3.9 m/s (2010).
The wettest September on record was 1986 with 181 mm. On average, September sees 69 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 Chatham 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.
