September is one of the warmer months of the year in Dover, with average highs near 26.3°C and lows around 16.3°C (mean 21.3°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 Dover. Across 45 years of records, the warmest September in Dover was 2005 — when the month averaged 23.6°C — while the coldest was 2000 at 19.1°C. Typical September days reach 26.3°C with nights near 16.3°C. The long-term trend is warming, about 0.5°C per decade.
September is about average for rainfall in Dover, averaging 102 mm of rainfall. The wettest September on record was 1999 with 280 mm, while the driest was 2005 at 9 mm.
Relative humidity in Dover during September averages 74%. The most humid September was 2011 at 86%, and the least humid was 1983 at 65%.
September receives about 4.4 kWh/m²/day of solar energy in Dover. The sunniest September was 2007 at 5.2 kWh/m²/day, and the cloudiest was 2018 at 3.5.
Average wind speed in Dover during September is 2.6 m/s. The windiest September was 1999 at 3.2 m/s, while the calmest was 2011 at 2.2 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 20.6°C | 20.8°C | 21.1°C | 22.1°C | 22.1°C | +1.5°C |
| Avg High | 25.9°C | 25.8°C | 26.0°C | 27.0°C | 27.0°C | +1.1°C |
| Avg Low | 15.3°C | 15.7°C | 16.1°C | 17.3°C | 17.2°C | +1.9°C |
| Avg Rain | 90 mm | 112 mm | 104 mm | 105 mm | 96 mm | +6 mm |
September temperatures in Dover have risen by about 1.8°C between 1981–1985 and 2021–2025.
September has ranged from a record low of 5.9°C (1992) to a record high of 36.2°C (1983).
Rainfall in September is about average for rainfall, averaging 102 mm, with a wettest year of 280 mm.
One of the best times to visit Dover
September is one of the best times to visit Dover. Expect days averaging 26.3°C and nights around 16.3°C (mean 21.3°C) — warmer than Dover'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 | 27.6°C | 22.4°C | 17.3°C | 33.4°C | 13.1°C | 88 mm | 74% | 2.5 m/s | 4.4 |
| 2024 | 27.4°C | 22.5°C | 17.6°C | 31.4°C | 11.6°C | 30 mm | 74% | 2.7 m/s | 4.2 |
| 2023 | 26.9°C | 22.2°C | 17.6°C | 35.7°C | 13.0°C | 169 mm | 76% | 2.6 m/s | 4.2 |
| 2022 | 27.5°C | 22.2°C | 16.8°C | 32.6°C | 9.9°C | 83 mm | 70% | 2.7 m/s | 4.7 |
| 2021 | 27.4°C | 22.5°C | 17.6°C | 31.2°C | 11.5°C | 91 mm | 76% | 2.8 m/s | 4.6 |
| 2020 | 25.0°C | 20.6°C | 16.2°C | 31.2°C | 7.2°C | 116 mm | 79% | 2.5 m/s | 4.3 |
| 2019 | 29.2°C | 23.5°C | 17.7°C | 34.5°C | 10.9°C | 23 mm | 69% | 2.5 m/s | 4.7 |
| 2018 | 27.1°C | 23.5°C | 19.8°C | 34.1°C | 13.8°C | 158 mm | 84% | 2.6 m/s | 3.5 |
| 2017 | 25.6°C | 21.1°C | 16.6°C | 30.1°C | 10.4°C | 62 mm | 77% | 2.4 m/s | 4.5 |
| 2016 | 27.9°C | 23.1°C | 18.3°C | 35.5°C | 11.9°C | 187 mm | 72% | 2.8 m/s | 4.3 |
| 2015 | 28.6°C | 23.3°C | 18.0°C | 34.3°C | 12.7°C | 89 mm | 73% | 2.6 m/s | 4.5 |
| 2014 | 26.4°C | 21.6°C | 16.8°C | 33.4°C | 10.6°C | 74 mm | 75% | 2.4 m/s | 4.5 |
| 2013 | 25.7°C | 20.1°C | 14.5°C | 33.8°C | 7.3°C | 31 mm | 71% | 2.3 m/s | 5.1 |
| 2012 | 25.8°C | 21.0°C | 16.3°C | 31.8°C | 8.9°C | 92 mm | 75% | 2.4 m/s | 4.6 |
| 2011 | 25.1°C | 21.3°C | 17.5°C | 28.5°C | 8.8°C | 170 mm | 86% | 2.2 m/s | 3.6 |
| 2010 | 28.4°C | 22.8°C | 17.2°C | 35.0°C | 11.4°C | 162 mm | 68% | 2.9 m/s | 4.7 |
| 2009 | 23.4°C | 19.4°C | 15.4°C | 28.1°C | 10.9°C | 132 mm | 82% | 2.8 m/s | 4.1 |
| 2008 | 27.2°C | 22.1°C | 17.0°C | 35.1°C | 12.4°C | 129 mm | 74% | 2.8 m/s | 4.3 |
| 2007 | 28.6°C | 22.8°C | 17.0°C | 33.4°C | 10.9°C | 28 mm | 68% | 2.3 m/s | 5.2 |
| 2006 | 24.9°C | 20.2°C | 15.4°C | 29.4°C | 9.6°C | 143 mm | 77% | 2.7 m/s | 3.9 |
| 2005 🔥 | 29.5°C | 23.6°C | 17.8°C | 33.9°C | 9.9°C | 9 mm | 66% | 2.3 m/s | 5.1 |
| 2004 | 26.4°C | 21.7°C | 17.0°C | 29.4°C | 10.6°C | 100 mm | 80% | 2.6 m/s | 4.1 |
| 2003 | 24.6°C | 20.6°C | 16.6°C | 28.3°C | 8.0°C | 168 mm | 84% | 2.9 m/s | 4.2 |
| 2002 | 26.6°C | 21.6°C | 16.6°C | 30.4°C | 12.6°C | 125 mm | 75% | 2.7 m/s | 4.8 |
| 2001 | 24.9°C | 19.6°C | 14.4°C | 29.4°C | 8.2°C | 61 mm | 73% | 2.5 m/s | 4.6 |
| 2000 ❄️ | 24.1°C | 19.1°C | 14.1°C | 29.1°C | 7.6°C | 143 mm | 79% | 2.6 m/s | 4.4 |
| 1999 🌧️ | 25.1°C | 20.6°C | 16.0°C | 30.5°C | 8.4°C | 280 mm | 81% | 3.2 m/s | 4.2 |
| 1998 | 28.8°C | 22.9°C | 17.1°C | 34.1°C | 9.8°C | 54 mm | 66% | 2.6 m/s | 4.8 |
| 1997 | 25.5°C | 20.3°C | 15.1°C | 31.4°C | 8.1°C | 56 mm | 71% | 2.8 m/s | 4.4 |
| 1996 | 25.0°C | 20.5°C | 16.1°C | 31.0°C | 10.0°C | 144 mm | 80% | 2.9 m/s | 4 |
| 1995 | 26.6°C | 21.1°C | 15.7°C | 33.1°C | 10.9°C | 95 mm | 66% | 2.5 m/s | 4.5 |
| 1994 | 25.0°C | 19.7°C | 14.5°C | 31.3°C | 9.9°C | 90 mm | 71% | 2.6 m/s | 4.6 |
| 1993 | 26.6°C | 21.6°C | 16.7°C | 34.9°C | 6.7°C | 105 mm | 71% | 2.7 m/s | 3.7 |
| 1992 | 24.4°C | 20.1°C | 15.7°C | 29.3°C | 5.9°C | 134 mm | 79% | 2.8 m/s | 4 |
| 1991 | 26.0°C | 20.7°C | 15.5°C | 33.9°C | 6.8°C | 107 mm | 69% | 2.6 m/s | 4.6 |
| 1990 | 25.3°C | 20.0°C | 14.7°C | 32.8°C | 6.2°C | 55 mm | 72% | 2.5 m/s | 4.4 |
| 1989 | 24.3°C | 20.2°C | 16.0°C | 31.7°C | 7.3°C | 143 mm | 81% | 2.7 m/s | 4.2 |
| 1988 | 25.2°C | 19.7°C | 14.2°C | 30.6°C | 9.6°C | 66 mm | 71% | 2.4 m/s | 4.5 |
| 1987 | 26.6°C | 21.7°C | 16.8°C | 31.0°C | 10.6°C | 107 mm | 74% | 2.4 m/s | 4.2 |
| 1986 | 26.3°C | 21.0°C | 15.7°C | 31.9°C | 7.4°C | 33 mm | 71% | 2.5 m/s | 4.3 |
| 1985 | 26.1°C | 21.0°C | 15.8°C | 32.8°C | 8.3°C | 163 mm | 72% | 2.4 m/s | 4.6 |
| 1984 | 25.5°C | 19.8°C | 14.0°C | 33.5°C | 7.5°C | 49 mm | 69% | 2.5 m/s | 4.9 |
| 1983 | 27.4°C | 21.5°C | 15.5°C | 36.2°C | 7.2°C | 92 mm | 65% | 2.5 m/s | — |
| 1982 | 26.3°C | 20.7°C | 15.2°C | 31.3°C | 10.3°C | 62 mm | 70% | 2.3 m/s | — |
| 1981 | 25.8°C | 20.2°C | 14.6°C | 32.5°C | 6.9°C | 98 mm | 69% | 2.7 m/s | — |
Actual recorded September data for each year, 1981–2025 — sourced from NASA POWER.
The average high in September is around 26.3°C with lows near 16.3°C (mean 21.3°C), based on 45 years of NASA POWER data.
September averages 102 mm of rainfall in Dover, about average for rainfall. The wettest on record was 280 mm in 1999.
The hottest September reached 36.2°C in 1983. The coldest dipped to 5.9°C in 1992.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average September temperatures have risen by about 1.8°C. Daytime highs moved from 26.2°C to 27.4°C and overnight lows from 15°C to 17.4°C over the same span.
September is one of the warmer months of the year in Dover and about average for rainfall, so plan for around 26.3°C daytime highs and 16.3°C at night.
Not quite — September is the 9th coolest month in Dover, averaging 21.3°C.
For September in Dover, pack light layers you can adjust through the day, with typical highs of 26.3°C and lows of 16.3°C. Bring an umbrella or light rain jacket too.
Relative humidity in September averages 74% — moderately humid.
Average wind speed in September is 2.6 m/s. The windiest September on record averaged 3.2 m/s (1999).
The wettest September on record was 1999 with 280 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 Dover 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.
