September is one of the warmer months of the year in New Britain, with average highs near 24°C and lows around 13.4°C (mean 18.7°C). It is about average for rainfall, averaging 102 mm of rainfall and 74% relative humidity across the period.
September is one of the warmer months of the year in New Britain. Across 45 years of records, the warmest September in New Britain was 2015 — when the month averaged 21.4°C — while the coldest was 1984 at 16.3°C. Typical September days reach 24°C with nights near 13.4°C. The long-term trend is warming, about 0.6°C per decade.
September is about average for rainfall in New Britain, averaging 102 mm of rainfall. The wettest September on record was 2023 with 233 mm, while the driest was 2024 at 26 mm.
Relative humidity in New Britain during September averages 74%. The most humid September was 2011 at 85%, and the least humid was 1983 at 63%.
September receives about 4.3 kWh/m²/day of solar energy in New Britain. The sunniest September was 2007 at 5 kWh/m²/day, and the cloudiest was 2018 at 3.4.
Average wind speed in New Britain during September is 0.5 m/s. The windiest Septembers were 2021, 2022 and 2023, among others at 0.6 m/s, while the calmest were 2020, 2024 and 2025, among others at 0.5 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 17.8°C | 18.0°C | 18.9°C | 19.7°C | 19.4°C | +1.6°C |
| Avg High | 23.4°C | 23.2°C | 24.3°C | 25.0°C | 24.5°C | +1.1°C |
| Avg Low | 12.2°C | 12.8°C | 13.6°C | 14.4°C | 14.3°C | +2.1°C |
| Avg Rain | 78 mm | 110 mm | 107 mm | 96 mm | 123 mm | +45 mm |
September temperatures in New Britain have risen by about 1.5°C between 1981–1985 and 2021–2025.
September has ranged from a record low of 2.1°C (2000) to a record high of 35.1°C (2010).
Rainfall in September is about average for rainfall, averaging 102 mm, with a wettest year of 233 mm.
One of the best times to visit New Britain
September is one of the best times to visit New Britain. Expect days averaging 24°C and nights around 13.4°C (mean 18.7°C) — warmer than New Britain's yearly average — with higher rainfall (102 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 | 25.6°C | 20.2°C | 14.7°C | 28.9°C | 10.6°C | 78 mm | 73% | 0.5 m/s | 4.6 |
| 2024 | 24.6°C | 19.1°C | 13.6°C | 29.6°C | 10.1°C | 26 mm | 74% | 0.5 m/s | 4.3 |
| 2023 🌧️ | 24.3°C | 19.7°C | 15.1°C | 34.6°C | 8.5°C | 233 mm | 80% | 0.6 m/s | 3.9 |
| 2022 | 23.9°C | 18.8°C | 13.8°C | 29.9°C | 6.4°C | 149 mm | 77% | 0.6 m/s | 4.4 |
| 2021 | 24.1°C | 19.6°C | 15.1°C | 27.8°C | 9.2°C | 196 mm | 80% | 0.6 m/s | 4.2 |
| 2020 | 24.7°C | 19.2°C | 13.7°C | 30.4°C | 5.0°C | 57 mm | 71% | 0.5 m/s | 4.4 |
| 2019 | 24.9°C | 19.3°C | 13.6°C | 30.5°C | 6.8°C | 47 mm | 72% | 0.5 m/s | 4.6 |
| 2018 | 24.5°C | 20.2°C | 15.9°C | 33.8°C | 8.6°C | 207 mm | 82% | 0.5 m/s | 3.4 |
| 2017 | 25.5°C | 20.3°C | 15.0°C | 33.8°C | 8.0°C | 62 mm | 74% | 0.5 m/s | 4.3 |
| 2016 | 25.9°C | 20.6°C | 15.3°C | 32.9°C | 6.4°C | 58 mm | 70% | 0.6 m/s | 4.2 |
| 2015 🔥 | 27.6°C | 21.4°C | 15.3°C | 34.6°C | 7.9°C | 104 mm | 72% | 0.5 m/s | 4.8 |
| 2014 | 25.1°C | 19.3°C | 13.6°C | 31.6°C | 7.2°C | 37 mm | 70% | 0.5 m/s | 4.5 |
| 2013 | 23.5°C | 17.7°C | 11.8°C | 32.5°C | 5.7°C | 61 mm | 73% | 0.5 m/s | 4.6 |
| 2012 | 23.7°C | 18.6°C | 13.5°C | 31.5°C | 7.0°C | 122 mm | 76% | 0.6 m/s | 4.3 |
| 2011 | 23.7°C | 19.5°C | 15.4°C | 27.0°C | 7.5°C | 183 mm | 85% | 0.5 m/s | 4.1 |
| 2010 | 25.4°C | 20.3°C | 15.1°C | 35.1°C | 7.9°C | 82 mm | 72% | 0.6 m/s | 4.3 |
| 2009 | 22.9°C | 17.6°C | 12.3°C | 28.7°C | 6.3°C | 50 mm | 74% | 0.6 m/s | 4.6 |
| 2008 | 23.6°C | 18.6°C | 13.6°C | 31.6°C | 7.4°C | 217 mm | 80% | 0.5 m/s | 4.2 |
| 2007 | 26.0°C | 20.0°C | 14.0°C | 30.9°C | 7.5°C | 52 mm | 70% | 0.5 m/s | 5 |
| 2006 | 22.1°C | 17.4°C | 12.7°C | 26.4°C | 6.7°C | 79 mm | 81% | 0.6 m/s | 4 |
| 2005 | 27.1°C | 21.1°C | 15.1°C | 33.4°C | 7.9°C | 63 mm | 68% | 0.5 m/s | 4.8 |
| 2004 | 24.4°C | 19.2°C | 14.0°C | 30.5°C | 7.7°C | 186 mm | 79% | 0.5 m/s | 4.3 |
| 2003 | 23.7°C | 19.0°C | 14.2°C | 27.9°C | 7.7°C | 119 mm | 79% | 0.5 m/s | 4 |
| 2002 | 25.3°C | 19.9°C | 14.5°C | 35.0°C | 8.4°C | 121 mm | 74% | 0.5 m/s | 4.4 |
| 2001 | 24.3°C | 18.6°C | 12.9°C | 29.6°C | 7.2°C | 99 mm | 71% | 0.5 m/s | 4.7 |
| 2000 | 23.4°C | 17.8°C | 12.3°C | 30.3°C | 2.1°C | 87 mm | 74% | 0.5 m/s | 4.2 |
| 1999 | 24.0°C | 19.3°C | 14.5°C | 32.1°C | 8.2°C | 182 mm | 79% | 0.6 m/s | 4 |
| 1998 | 25.3°C | 19.3°C | 13.4°C | 30.3°C | 4.9°C | 68 mm | 71% | 0.5 m/s | 4.5 |
| 1997 | 23.6°C | 18.0°C | 12.5°C | 28.3°C | 4.4°C | 32 mm | 71% | 0.5 m/s | 4.2 |
| 1996 | 22.8°C | 18.3°C | 13.7°C | 31.6°C | 6.7°C | 154 mm | 79% | 0.5 m/s | 3.6 |
| 1995 | 23.5°C | 17.8°C | 12.1°C | 29.9°C | 6.0°C | 94 mm | 68% | 0.6 m/s | 4.4 |
| 1994 | 22.3°C | 17.2°C | 12.2°C | 27.6°C | 8.1°C | 112 mm | 74% | 0.6 m/s | 4.2 |
| 1993 | 22.8°C | 17.9°C | 13.1°C | 31.4°C | 3.3°C | 140 mm | 76% | 0.5 m/s | 3.5 |
| 1992 | 22.1°C | 17.2°C | 12.2°C | 27.4°C | 3.9°C | 106 mm | 78% | 0.5 m/s | 4 |
| 1991 | 22.1°C | 16.9°C | 11.8°C | 30.8°C | 2.5°C | 141 mm | 75% | 0.5 m/s | 4.3 |
| 1990 | 23.1°C | 17.6°C | 12.2°C | 29.3°C | 4.0°C | 69 mm | 75% | 0.6 m/s | 4.4 |
| 1989 | 22.8°C | 17.7°C | 12.6°C | 31.8°C | 2.3°C | 115 mm | 79% | 0.6 m/s | 4.3 |
| 1988 | 23.2°C | 17.2°C | 11.3°C | 28.0°C | 5.8°C | 69 mm | 70% | 0.5 m/s | 4.7 |
| 1987 | 22.1°C | 17.4°C | 12.7°C | 27.5°C | 5.6°C | 132 mm | 80% | 0.5 m/s | 3.9 |
| 1986 | 23.2°C | 17.7°C | 12.2°C | 29.3°C | 5.3°C | 27 mm | 70% | 0.5 m/s | 4 |
| 1985 | 23.4°C | 18.0°C | 12.6°C | 29.2°C | 6.0°C | 86 mm | 76% | 0.5 m/s | 4.4 |
| 1984 ❄️ | 22.0°C | 16.3°C | 10.6°C | 28.1°C | 5.2°C | 56 mm | 70% | 0.5 m/s | 4.6 |
| 1983 | 26.6°C | 20.0°C | 13.4°C | 34.0°C | 6.2°C | 57 mm | 63% | 0.5 m/s | — |
| 1982 | 24.0°C | 18.1°C | 12.3°C | 30.5°C | 9.1°C | 64 mm | 72% | 0.5 m/s | — |
| 1981 | 23.1°C | 17.5°C | 11.9°C | 29.6°C | 3.2°C | 96 mm | 70% | 0.6 m/s | — |
Actual recorded September data for each year, 1981–2025 — sourced from NASA POWER.
The average high in September is around 24°C with lows near 13.4°C (mean 18.7°C), based on 45 years of NASA POWER data.
September averages 102 mm of rainfall in New Britain, about average for rainfall. The wettest on record was 233 mm in 2023.
The hottest September reached 35.1°C in 2010. The coldest dipped to 2.1°C in 2000.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average September temperatures have risen by about 1.5°C. Daytime highs moved from 23.8°C to 24.5°C and overnight lows from 12.2°C to 14.5°C over the same span.
September is one of the warmer months of the year in New Britain and about average for rainfall, so plan for around 24°C daytime highs and 13.4°C at night.
Not quite — September is the 9th coolest month in New Britain, averaging 18.7°C.
For September in New Britain, pack light layers you can adjust through the day, with typical highs of 24°C and lows of 13.4°C. Bring an umbrella or light rain jacket too.
Relative humidity in September averages 74% — moderately humid.
Average wind speed in September is 0.5 m/s. The windiest September on record averaged 0.6 m/s (1981).
The wettest September on record was 2023 with 233 mm. On average, September sees 102 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 New Britain 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.
