September is one of the warmer months of the year in Dover, with average highs near 17.8°C and lows around 14.3°C (mean 16.1°C). It is about average for rainfall, averaging 62 mm of rainfall and 82% 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 2023 — when the month averaged 18.8°C — while the coldest was 1986 at 13.5°C. Typical September days reach 17.8°C with nights near 14.3°C. The long-term trend is warming, about 0.4°C per decade.
September is about average for rainfall in Dover, averaging 62 mm of rainfall. The wettest September on record was 1993 with 123 mm, while the driest was 1997 at 8 mm.
Relative humidity in Dover during September averages 82%. The most humid September was 1999 at 86%, and the least humid was 1990 at 76%.
September receives about 3.2 kWh/m²/day of solar energy in Dover. The sunniest September was 2003 at 3.8 kWh/m²/day, and the cloudiest were 1984 and 2000 at 2.6.
Average wind speed in Dover during September is 5.1 m/s. The windiest September was 2025 at 6.4 m/s, while the calmest was 2014 at 3.7 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 15.6°C | 15.5°C | 16.3°C | 16.0°C | 17.2°C | +1.6°C |
| Avg High | 17.3°C | 17.3°C | 18.0°C | 17.8°C | 19.0°C | +1.7°C |
| Avg Low | 13.8°C | 13.7°C | 14.5°C | 14.2°C | 15.4°C | +1.6°C |
| Avg Rain | 59 mm | 77 mm | 50 mm | 57 mm | 71 mm | +12 mm |
September temperatures in Dover have risen by about 1.6°C between 1981–1985 and 2021–2025.
September has ranged from a record low of 9.5°C (1995) to a record high of 24.5°C (2023).
Rainfall in September is about average for rainfall, averaging 62 mm, with a wettest year of 123 mm.
One of the best times to visit Dover
September is one of the best times to visit Dover. Expect days averaging 17.8°C and nights around 14.3°C (mean 16.1°C) — warmer than Dover's yearly average — with moderate rainfall (62 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 | 18.4°C | 16.7°C | 14.9°C | 22.6°C | 12.2°C | 52 mm | 78% | 6.4 m/s | 3.4 |
| 2024 | 18.4°C | 16.7°C | 15.0°C | 24.2°C | 10.4°C | 115 mm | 83% | 5.4 m/s | 3.1 |
| 2023 🔥 | 20.8°C | 18.8°C | 16.9°C | 24.5°C | 12.8°C | 60 mm | 83% | 4.3 m/s | 3.5 |
| 2022 | 18.6°C | 17.0°C | 15.4°C | 22.3°C | 10.8°C | 104 mm | 78% | 4.7 m/s | 3.2 |
| 2021 | 19.4°C | 17.6°C | 15.8°C | 23.7°C | 11.9°C | 37 mm | 83% | 4.5 m/s | 3.2 |
| 2020 | 18.5°C | 16.6°C | 14.6°C | 22.9°C | 9.6°C | 57 mm | 81% | 5.4 m/s | 3.3 |
| 2019 | 18.3°C | 16.4°C | 14.6°C | 20.7°C | 12.5°C | 66 mm | 79% | 5.9 m/s | 3.4 |
| 2018 | 17.9°C | 16.1°C | 14.4°C | 20.3°C | 10.8°C | 47 mm | 78% | 5.2 m/s | 3.5 |
| 2017 | 17.2°C | 15.5°C | 13.8°C | 19.0°C | 11.5°C | 71 mm | 81% | 5.1 m/s | 3.2 |
| 2016 | 19.4°C | 17.8°C | 16.1°C | 23.2°C | 13.9°C | 47 mm | 83% | 4.7 m/s | 3.2 |
| 2015 | 16.4°C | 14.7°C | 13.0°C | 18.7°C | 11.2°C | 100 mm | 80% | 5.2 m/s | 3.3 |
| 2014 | 18.6°C | 17.0°C | 15.3°C | 21.6°C | 12.2°C | 14 mm | 85% | 3.7 m/s | 3.1 |
| 2013 | 17.5°C | 15.6°C | 13.6°C | 22.3°C | 11.1°C | 59 mm | 84% | 4.7 m/s | 3 |
| 2012 | 17.0°C | 15.2°C | 13.4°C | 20.4°C | 10.6°C | 57 mm | 80% | 5.1 m/s | 3.5 |
| 2011 | 18.2°C | 16.3°C | 14.4°C | 20.9°C | 11.4°C | 44 mm | 85% | 5.7 m/s | 3.4 |
| 2010 | 17.1°C | 15.3°C | 13.6°C | 19.3°C | 10.1°C | 65 mm | 83% | 5.1 m/s | 3.1 |
| 2009 | 18.0°C | 16.5°C | 15.0°C | 20.8°C | 13.3°C | 26 mm | 80% | 5.3 m/s | 3.3 |
| 2008 | 16.8°C | 15.3°C | 13.9°C | 20.3°C | 11.7°C | 69 mm | 79% | 5.6 m/s | 3 |
| 2007 | 17.4°C | 15.8°C | 14.1°C | 19.8°C | 11.2°C | 45 mm | 81% | 5.1 m/s | 3.4 |
| 2006 | 19.7°C | 18.0°C | 16.2°C | 22.4°C | 14.2°C | 41 mm | 86% | 4.8 m/s | 3.4 |
| 2005 | 18.6°C | 16.9°C | 15.1°C | 22.7°C | 11.5°C | 50 mm | 83% | 4.3 m/s | 3.3 |
| 2004 | 18.1°C | 16.2°C | 14.3°C | 21.5°C | 10.6°C | 25 mm | 83% | 6 m/s | 3.3 |
| 2003 | 18.6°C | 16.5°C | 14.3°C | 22.0°C | 11.1°C | 20 mm | 76% | 3.8 m/s | 3.8 |
| 2002 | 17.7°C | 16.1°C | 14.5°C | 19.8°C | 11.0°C | 51 mm | 81% | 5 m/s | 3.3 |
| 2001 | 16.5°C | 14.9°C | 13.2°C | 19.5°C | 11.0°C | 90 mm | 83% | 5.7 m/s | 2.9 |
| 2000 | 18.1°C | 16.5°C | 14.8°C | 21.8°C | 13.2°C | 85 mm | 86% | 5.4 m/s | 2.6 |
| 1999 | 19.0°C | 17.3°C | 15.6°C | 23.3°C | 13.4°C | 108 mm | 86% | 5.2 m/s | 3 |
| 1998 | 17.8°C | 16.0°C | 14.1°C | 20.5°C | 10.7°C | 111 mm | 86% | 5.4 m/s | 3 |
| 1997 | 17.9°C | 16.0°C | 14.1°C | 20.1°C | 11.6°C | 8 mm | 80% | 4.7 m/s | 3.5 |
| 1996 | 16.3°C | 14.7°C | 13.1°C | 18.4°C | 10.5°C | 43 mm | 80% | 5.6 m/s | 3.1 |
| 1995 | 17.2°C | 15.5°C | 13.9°C | 19.7°C | 9.5°C | 120 mm | 81% | 5.6 m/s | 2.9 |
| 1994 | 16.3°C | 14.7°C | 13.2°C | 19.3°C | 9.8°C | 96 mm | 83% | 5.5 m/s | 2.9 |
| 1993 🌧️ | 15.9°C | 14.3°C | 12.7°C | 19.0°C | 10.0°C | 123 mm | 84% | 5.1 m/s | 2.7 |
| 1992 | 16.9°C | 15.1°C | 13.2°C | 20.4°C | 10.8°C | 70 mm | 84% | 5.4 m/s | 3.1 |
| 1991 | 18.1°C | 16.2°C | 14.4°C | 22.0°C | 10.7°C | 56 mm | 81% | 4.5 m/s | 3.3 |
| 1990 | 17.2°C | 15.2°C | 13.1°C | 20.8°C | 10.1°C | 39 mm | 76% | 5.2 m/s | 2.9 |
| 1989 | 18.5°C | 16.9°C | 15.3°C | 21.7°C | 13.1°C | 43 mm | 82% | 4.8 m/s | 3 |
| 1988 | 16.7°C | 15.1°C | 13.4°C | 20.0°C | 10.0°C | 66 mm | 83% | 5.8 m/s | 2.7 |
| 1987 | 17.5°C | 15.8°C | 14.0°C | 21.7°C | 10.5°C | 47 mm | 83% | 4.6 m/s | 2.9 |
| 1986 ❄️ | 15.2°C | 13.5°C | 11.8°C | 17.9°C | 10.5°C | 52 mm | 81% | 4.8 m/s | 3 |
| 1985 | 17.6°C | 15.7°C | 13.8°C | 20.7°C | 11.1°C | 16 mm | 84% | 4.6 m/s | 3.1 |
| 1984 | 16.7°C | 15.0°C | 13.3°C | 20.3°C | 10.4°C | 83 mm | 82% | 5.7 m/s | 2.6 |
| 1983 | 17.2°C | 15.3°C | 13.4°C | 19.7°C | 10.6°C | 77 mm | 83% | 6.3 m/s | — |
| 1982 | 18.6°C | 16.6°C | 14.6°C | 22.9°C | 11.7°C | 57 mm | 83% | 4.5 m/s | — |
| 1981 | 17.9°C | 16.3°C | 14.6°C | 20.7°C | 11.1°C | 89 mm | 82% | 5.4 m/s | — |
Actual recorded September data for each year, 1981–2025 — sourced from NASA POWER.
The average high in September is around 17.8°C with lows near 14.3°C (mean 16.1°C), based on 45 years of NASA POWER data.
September averages 62 mm of rainfall in Dover, about average for rainfall. The wettest on record was 123 mm in 1993.
The hottest September reached 24.5°C in 2023. The coldest dipped to 9.5°C in 1995.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average September temperatures have risen by about 1.6°C. Daytime highs moved from 17.6°C to 19.1°C and overnight lows from 13.9°C to 15.6°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 17.8°C daytime highs and 14.3°C at night.
Not quite — September is the 10th coolest month in Dover, averaging 16.1°C.
For September in Dover, pack light layers you can adjust through the day, with typical highs of 17.8°C and lows of 14.3°C. Bring an umbrella or light rain jacket too.
Relative humidity in September averages 82% — quite humid.
Average wind speed in September is 5.1 m/s. The windiest September on record averaged 6.4 m/s (2025).
The wettest September on record was 1993 with 123 mm. On average, September sees 62 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.
