September is one of the warmer months of the year in Middletown, with average highs near 23.7°C and lows around 11.5°C (mean 17.6°C). It is a relatively wet time of year, averaging 112 mm of rainfall and 74% relative humidity across the period.
September is one of the warmer months of the year in Middletown. Across 45 years of records, the warmest September in Middletown was 2005 — when the month averaged 20.5°C — while the coldest was 1984 at 14.6°C. Typical September days reach 23.7°C with nights near 11.5°C. The long-term trend is warming, about 0.6°C per decade.
September is a relatively wet time of year in Middletown, averaging 112 mm of rainfall. The wettest September on record was 2011 with 290 mm, while the driest was 2019 at 23 mm.
Relative humidity in Middletown during September averages 74%. The most humid September was 2011 at 88%, and the least humid was 2005 at 61%.
September receives about 4.1 kWh/m²/day of solar energy in Middletown. The sunniest Septembers were 2005, 2007 and 2013, among others at 4.8 kWh/m²/day, and the cloudiest was 2018 at 3.
Average wind speed in Middletown during September is 0.1 m/s. The windiest September was 1982 at 0.2 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 | 16.7°C | 16.9°C | 17.7°C | 18.6°C | 18.3°C | +1.6°C |
| Avg High | 23.0°C | 22.9°C | 23.7°C | 24.7°C | 24.2°C | +1.2°C |
| Avg Low | 10.4°C | 10.8°C | 11.6°C | 12.5°C | 12.5°C | +2.1°C |
| Avg Rain | 99 mm | 116 mm | 117 mm | 111 mm | 119 mm | +20 mm |
September temperatures in Middletown have risen by about 1.4°C between 1981–1985 and 2021–2025.
September has ranged from a record low of -0.5°C (1991) to a record high of 34.9°C (2015).
Rainfall in September is a relatively wet time of year, averaging 112 mm, with a wettest year of 290 mm.
One of the best times to visit Middletown
September is one of the best times to visit Middletown. Expect days averaging 23.7°C and nights around 11.5°C (mean 17.6°C) — warmer than Middletown's yearly average — with higher rainfall (112 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 | 25.9°C | 19.5°C | 13.0°C | 29.5°C | 8.5°C | 60 mm | 69% | 0.1 m/s | 4.4 |
| 2024 | 24.8°C | 18.6°C | 12.3°C | 29.8°C | 7.4°C | 47 mm | 72% | 0.1 m/s | 4.3 |
| 2023 | 23.4°C | 18.2°C | 13.0°C | 32.5°C | 6.7°C | 175 mm | 82% | 0.1 m/s | 4 |
| 2022 | 23.7°C | 18.0°C | 12.2°C | 30.0°C | 4.8°C | 120 mm | 75% | 0.1 m/s | 4.1 |
| 2021 | 23.0°C | 17.9°C | 12.7°C | 27.6°C | 6.3°C | 221 mm | 83% | 0.1 m/s | 4.1 |
| 2020 | 24.3°C | 17.9°C | 11.6°C | 30.2°C | 3.1°C | 91 mm | 71% | 0.1 m/s | 4.2 |
| 2019 | 25.5°C | 18.8°C | 12.1°C | 31.9°C | 5.7°C | 23 mm | 68% | 0.1 m/s | 4.2 |
| 2018 | 23.7°C | 19.0°C | 14.3°C | 31.5°C | 6.5°C | 191 mm | 86% | 0.1 m/s | 3 |
| 2017 | 25.0°C | 19.1°C | 13.1°C | 33.1°C | 6.6°C | 61 mm | 73% | 0.1 m/s | 4.4 |
| 2016 | 26.3°C | 19.8°C | 13.4°C | 33.2°C | 4.8°C | 51 mm | 65% | 0.1 m/s | 4.5 |
| 2015 | 26.6°C | 20.0°C | 13.4°C | 34.9°C | 7.8°C | 134 mm | 70% | 0.1 m/s | 4.6 |
| 2014 | 25.3°C | 18.5°C | 11.8°C | 33.2°C | 5.0°C | 25 mm | 67% | 0.1 m/s | 4.4 |
| 2013 | 23.0°C | 16.2°C | 9.5°C | 33.0°C | 2.6°C | 59 mm | 72% | 0.1 m/s | 4.8 |
| 2012 | 23.4°C | 17.4°C | 11.5°C | 31.4°C | 4.9°C | 170 mm | 76% | 0.1 m/s | 4.1 |
| 2011 🌧️ | 22.8°C | 18.2°C | 13.5°C | 28.5°C | 4.5°C | 290 mm | 88% | 0.1 m/s | 3.4 |
| 2010 | 24.9°C | 18.8°C | 12.6°C | 34.0°C | 6.6°C | 105 mm | 70% | 0.1 m/s | 4.2 |
| 2009 | 21.6°C | 16.0°C | 10.5°C | 26.3°C | 4.5°C | 51 mm | 78% | 0.1 m/s | 4.1 |
| 2008 | 23.7°C | 17.9°C | 12.1°C | 33.6°C | 5.4°C | 162 mm | 77% | 0.1 m/s | 4.2 |
| 2007 | 26.2°C | 19.2°C | 12.3°C | 32.5°C | 4.8°C | 42 mm | 68% | 0.1 m/s | 4.8 |
| 2006 | 21.1°C | 16.0°C | 10.8°C | 26.6°C | 4.5°C | 113 mm | 81% | 0.1 m/s | 3.6 |
| 2005 🔥 | 27.7°C | 20.5°C | 13.4°C | 34.1°C | 6.1°C | 35 mm | 61% | 0.1 m/s | 4.8 |
| 2004 | 23.2°C | 17.8°C | 12.3°C | 28.7°C | 5.7°C | 236 mm | 84% | 0.1 m/s | 4 |
| 2003 | 21.8°C | 17.0°C | 12.1°C | 26.0°C | 4.6°C | 228 mm | 85% | 0.1 m/s | 3.7 |
| 2002 | 25.7°C | 19.0°C | 12.4°C | 34.5°C | 6.2°C | 100 mm | 67% | 0.1 m/s | 4.5 |
| 2001 | 24.2°C | 17.2°C | 10.2°C | 31.4°C | 4.2°C | 104 mm | 67% | 0.1 m/s | 4.5 |
| 2000 | 22.3°C | 16.0°C | 9.7°C | 29.9°C | -0.2°C | 101 mm | 75% | 0.1 m/s | 4 |
| 1999 | 23.5°C | 17.8°C | 12.2°C | 32.9°C | 5.4°C | 259 mm | 77% | 0.1 m/s | 4 |
| 1998 | 25.5°C | 18.5°C | 11.5°C | 31.7°C | 3.6°C | 66 mm | 69% | 0.1 m/s | 4.3 |
| 1997 | 22.3°C | 16.3°C | 10.2°C | 28.9°C | 2.1°C | 88 mm | 71% | 0.1 m/s | 4.4 |
| 1996 | 22.2°C | 17.2°C | 12.1°C | 30.5°C | 4.9°C | 168 mm | 80% | 0.1 m/s | 3.5 |
| 1995 | 23.3°C | 16.7°C | 10.1°C | 30.4°C | 3.4°C | 86 mm | 65% | 0.1 m/s | 4.1 |
| 1994 | 22.0°C | 16.1°C | 10.2°C | 27.5°C | 6.0°C | 97 mm | 76% | 0.1 m/s | 4 |
| 1993 | 22.5°C | 17.0°C | 11.4°C | 31.5°C | 2.3°C | 143 mm | 75% | 0.1 m/s | 3.2 |
| 1992 | 22.6°C | 16.6°C | 10.7°C | 29.6°C | 1.4°C | 83 mm | 74% | 0.1 m/s | 3.9 |
| 1991 | 23.3°C | 16.6°C | 10.0°C | 33.7°C | -0.5°C | 119 mm | 68% | 0.1 m/s | 4.3 |
| 1990 | 21.8°C | 15.9°C | 9.9°C | 28.0°C | 1.3°C | 48 mm | 76% | 0.1 m/s | 4.2 |
| 1989 | 23.1°C | 17.1°C | 11.0°C | 33.6°C | 1.5°C | 167 mm | 76% | 0.1 m/s | 3.9 |
| 1988 | 22.5°C | 15.9°C | 9.2°C | 27.9°C | 3.4°C | 64 mm | 72% | 0.1 m/s | 4.4 |
| 1987 | 21.1°C | 15.9°C | 10.8°C | 25.5°C | 3.0°C | 190 mm | 83% | 0.1 m/s | 3.9 |
| 1986 | 23.0°C | 16.8°C | 10.6°C | 29.2°C | 2.7°C | 44 mm | 72% | 0.1 m/s | 3.7 |
| 1985 | 24.3°C | 17.7°C | 11.2°C | 30.5°C | 4.1°C | 155 mm | 72% | 0.1 m/s | 4.4 |
| 1984 ❄️ | 20.9°C | 14.6°C | 8.4°C | 27.9°C | 3.1°C | 42 mm | 74% | 0.1 m/s | 4.8 |
| 1983 | 25.6°C | 18.4°C | 11.1°C | 33.8°C | 3.6°C | 73 mm | 61% | 0.1 m/s | — |
| 1982 | 24.1°C | 17.5°C | 10.9°C | 30.5°C | 6.0°C | 67 mm | 69% | 0.2 m/s | — |
| 1981 | 22.4°C | 16.6°C | 10.8°C | 30.0°C | 1.4°C | 87 mm | 70% | 0.1 m/s | — |
Actual recorded September data for each year, 1981–2025 — sourced from NASA POWER.
The average high in September is around 23.7°C with lows near 11.5°C (mean 17.6°C), based on 45 years of NASA POWER data.
September averages 112 mm of rainfall in Middletown, a relatively wet time of year. The wettest on record was 290 mm in 2011.
The hottest September reached 34.9°C in 2015. The coldest dipped to -0.5°C in 1991.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average September temperatures have risen by about 1.4°C. Daytime highs moved from 23.5°C to 24.2°C and overnight lows from 10.5°C to 12.6°C over the same span.
September is one of the warmer months of the year in Middletown and a relatively wet time of year, so plan for around 23.7°C daytime highs and 11.5°C at night.
Not quite — September is the 9th coolest month in Middletown, averaging 17.6°C.
For September in Middletown, pack light layers you can adjust through the day, with typical highs of 23.7°C and lows of 11.5°C. Bring an umbrella or light rain jacket too.
Relative humidity in September averages 74% — moderately humid.
Average wind speed in September is 0.1 m/s. The windiest September on record averaged 0.2 m/s (1982).
The wettest September on record was 2011 with 290 mm. On average, September sees 112 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 Middletown 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.
