Dover weather in September

In September, Dover sees average daytime highs of 77°F and overnight lows near 63°F, with 4.1 in of rain across 9.2 wet days and about 12.3 hours of daylight. It is the 4th-warmest and 3rd-wettest month of the year here.

Highs ease over the month, from about 81°F in the first days to 73°F by the end. The sky is clear or mostly clear about 38% of the time in September, and the air most often feels dry.

Daylight stretches from about 12 h 54 min at the start of September to 11 h 36 min by month's end. Set against the rest of the year, September is Dover's 3rd-clearest and 9th-windiest month. For the whole year in context, see Dover's year-round climate.

Daytime high
77°
4th warmest
Overnight low
63°
9th coldest
Rainfall
4.1 in
9.2 wet days
Daylight
12 h 18 min
5:49 AM – 6:04 PM
Cloud cover
55%
3rd clearest
Wind
7 mph
9th windiest
Solar energy
4.42 kWh/m²
Travel score
7.0
out of 10

Dover is capital city of the U.S. state of Delaware and seat of Kent County.

Density
648/km²
people per km²
Founded
1683

Air quality: WHO Ambient Air Quality Database. Density & description: Wikidata (CC0), GeoNames.

Temperature in September

Average highAverage lowShaded bands: 10–90% of days

Highs ease over the month, from about 81°F in the first days to 73°F by the end.

A typical September day in Dover reaches about 77°F in the afternoon and slips back to 63°F overnight — a 14°F spread between the day's warmth and the night's chill. On most days the high lands between 70°F and 85°F. Set against its neighbours, September runs about 6°F cooler than August and about 11°F warmer than October.

40°60°80°151015202530
Avg high (°F)Avg low (°F)
18168
28167
38167
48167
58167
68067
78066
88066
98066
107965
117965
127965
137864
147864
157864
167763
177763
187763
197662
207662
217662
227561
237561
247561
257460
267460
277460
287359
297359
307358

How September really feels in Dover

Once humidity and wind are folded in, September averages 0 days that feel above 90°F and 0 that feel at or below 32°F — the comfort signal a plain temperature reading hides.

Days feeling ≥ 90°F
0
heat index over the day's high
Days feeling ≤ 32°F
0
wind chill below the day's low

September sits comfortably in between — no days that feel dangerously hot or drop to a hard freeze once humidity and wind are folded in.

Dover weather by month

How September compares with the rest of the year at a glance. September is the 4th-warmest and 3rd-wettest month here — the current month is highlighted below.

MonthHigh / Low (°F)Rainfall (inches)Wet daysSnow daysDaylight (hours)Travel score
Jan43° / 30°3.19.22.99.60.4
Feb45° / 31°3.08.92.910.51.0
Mar53° / 38°4.110.31.611.72.9
Apr64° / 47°3.39.90.2135.6
May72° / 57°3.410.7014.16.6
Jun81° / 66°3.610.2014.76.2
Jul85° / 71°3.711014.55.2
Aug83° / 70°4.310.5013.55.8
Sep77° / 63°4.19.2012.37.0
Oct67° / 52°3.780116.5
Nov56° / 42°2.97.50.29.94.0
Dec47° / 35°3.79.11.39.31.6

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 38% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 16% of September, with mostly cloudy or overcast conditions the remaining 46%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
15743
25644
35644
45644
55644
65644
75644
85545
95545
105545
115545
125545
135446
145545
155446
165347
175347
185248
195149
205149
215149
225149
235248
245248
255248
265248
275347
285347
295347
305446

Chance of precipitation in September

Any precipitation

Dover gets around 4.1 in of rain over 9.2 wet days in September. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 29% and peaks near 31% on the wettest days.

0%10%20%30%40%151015202530
Rain chance (%)
128
228
329
429
529
629
729
829
929
1029
1129
1229
1328
1428
1528
1628
1728
1829
1929
2029
2130
2230
2331
2431
2531
2631
2730
2830
2930
3030

Humidity in September

DryComfortableHumidMuggyOppressiveMiserable

Most of September feels dry — the stacked bands show each day's mix of comfort levels, read off the dew point.

By dew point, September lands in the dry band about 28% of days. Sticky, muggy-or-worse air turns up on roughly 31% of them.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)Miserable (%)
110182526201
211182526201
312182525191
413182524191
514192523181
615192523171
716192522171
818192522160
919192521150
1020192521140
1122192521130
1223192421120
1325192421110
1426192422100
152819232290
162919232280
173019222170
183219222170
193319222160
203419212150
213519212150
223719202040
233819202040
244019191930
254119191830
264319181830
274419181720
284619181620
294718171520
304918171420

Wind in September

Winds average 7 mph in September.

Across September, daily wind ranges from about 7 mph on the calmest days to 8 mph at its breeziest. It stays fairly steady from day to day.

0246810151015202530
Wind speed (mph)Feels
17calm
27calm
37calm
47calm
57calm
67calm
77calm
87calm
97calm
107calm
117calm
127calm
137calm
147calm
157calm
167calm
177calm
187calm
197calm
207calm
217calm
227calm
237calm
247calm
257calm
267calm
277light breeze
288light breeze
298light breeze
308light breeze

Sunrise & sunset in September

DaylightNight

Daylight runs from about 12 h 54 min at the start of September to 11 h 36 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 78 minutes over September. Sunrise moves from 5:35 AM to 6:02 AM, and sunset from 6:29 PM to 5:41 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.95:356:29
212.95:366:27
312.85:376:26
412.85:386:24
512.75:396:22
612.75:406:21
712.65:406:19
812.65:416:17
912.65:426:16
1012.55:436:14
1112.55:446:12
1212.45:456:11
1312.45:466:09
1412.35:476:07
1512.35:486:06
1612.35:496:04
1712.25:506:02
1812.25:516:01
1912.15:525:59
2012.15:535:57
2112.05:545:56
2212.05:555:54
2311.95:555:52
2411.95:565:51
2511.95:575:49
2611.85:585:47
2711.85:595:46
2811.76:005:44
2911.76:015:42
3011.66:025:41

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 4.42 kWh/m².

For context, solar energy here swings from a low near 1.93 kWh/m² to a high of 6.33 kWh/m² in June across the year — September's 4.42 kWh/m² falls in the middle.

0246151015202530
Solar energy (kWh/m²)Level
15.0Bright
25.0Bright
34.9Bright
44.9Bright
54.9Bright
64.8Bright
74.8Bright
84.8Bright
94.7Bright
104.7Bright
114.6Bright
124.6Bright
134.5Bright
144.5Bright
154.5Bright
164.4Bright
174.4Bright
184.3Bright
194.3Bright
204.3Bright
214.2Bright
224.2Bright
234.1Bright
244.1Bright
254.1Bright
264.0Bright
274.0Moderate
284.0Moderate
293.9Moderate
303.9Moderate
Planning a trip in September

Hazard calendar for Dover

In seasonPeak

In September, Dover sits inside its atlantic hurricane season. The full year is below, with each hazard's peak months called out.

Dover sits in the Atlantic hurricane belt; the season peaks August–October.

Atlantic hurricane
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec

Is September a good time to visit Dover?

Our two travel scores rate September for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal).

7.0
Sightseeing
1st-best month of the year
6.3
Beach & pool
4th-best month of the year

September is one of the better times to visit Dover for general sightseeing. The water and warmth also suit a beach or pool day.

What to pack for Dover in September

From September's temperature range, rain chance, sun and wind — what's worth putting in the bag.

In September, Dover sees daytime highs around 77°F and nights near 63°F. Worth packing: light clothes and rain gear. About 9 days see rain.

light clothesrain gear

Sea temperature near Dover in September

The nearest coast averages about 73°F in September — the other half of the beach question. The full-year curve and swim-comfort zones are below.

The sea at the nearest coast (about 8 mi away) is warmest in August at about 76°F and coldest in February near 37°F.

It's comfortable for a long swim from Jun 19 to Oct 3 — about 3.5 months when the water holds above 68°F.

30°40°50°60°70°80°JanFebMarAprMayJunJulAugSepOctNovDecbracingcoolrefreshingwarmtropicalcomfortable to swim
Sea temperature (°F)Comfort
Jan39Bracing
Feb37Bracing
Mar41Bracing
Apr49Bracing
May58Bracing
Jun67Cool
Jul74Refreshing
Aug76Warm
Sep73Refreshing
Oct64Cool
Nov53Bracing
Dec44Bracing

UV index in Dover in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 6 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Dover peaks around July 10 at about 8 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near December 20 at about 2 (low).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 9 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecModerateHighVery highHighModerateLowJul 10UV 8Dec 20UV 2
UV index (midday)Level
Jan2Low
Feb3Moderate
Mar5Moderate
Apr6High
May8Very high
Jun8Very high
Jul9Very high
Aug6High
Sep6High
Oct4Moderate
Nov3Moderate
Dec2Low

Air quality in Dover in September

GoodModeratePoorUnhealthyVery unhealthy

Average fine-particle pollution (PM2.5) through the year — so you can see where September falls, not just the annual average.

Air quality in Dover is worst in July — around 16 µg/m³ PM2.5 (moderate), about 2.2× the cleanest month (November, 7 µg/m³).

Modeled monthly averages (CAMS reanalysis, 2015–2024).

01020JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodJul 1115 µg/m³Nov 127 µg/m³
PM2.5 (µg/m³)Level
Jan9Good
Feb11Good
Mar12Good
Apr12Good
May13Moderate
Jun15Moderate
Jul16Moderate
Aug13Moderate
Sep10Good
Oct8Good
Nov7Good
Dec8Good
Location & terrain

Where is Dover?

Dover sits at 39.2°N, 75.5°W, 30 ft above sea level, in United States. The nearest listed city is Middletown, 22 mi away.

Topography around Dover

How much the land rises and falls, and what covers it, within 2, 10 and 50 miles of Dover.

Within 2 miles, the terrain around Dover has only modest variations in elevation — a maximum elevation change of 131 ft around an average of 39 ft above sea level; within 10 miles, only modest variations in elevation — a maximum elevation change of 174 ft; within 50 miles, only modest variations in elevation — a maximum elevation change of 761 ft.

The land around Dover is covered by trees (41%), artificial surfaces (29%) and grassland (21%) within 2 miles, trees (30%) and cropland (26%) within 10 miles, and trees (39%), water (27%) and cropland (20%) within 50 miles.

2 miles
131 ft
10 miles
174 ft
50 miles
761 ft
treesgrasslandcroplandartificial surfacesbare terrainwaterwetland
September weather nearby: Middletown 22 mi · Bridgeton 24 mi · Millville 31 mi · South Vineland 33 mi · Bear 34 mi · Vineland 35 mi · Elkton 35 mi · Cape May 37 mi

United States travel facts

Power plugs
Type A / B
120 V · 60 Hz
Prices
≈ 100% of US
price level, 2025
GDP per capita
$90,027
2025
Happiness
6.8 / 10
World Happiness, 2025
Safe drinking water
98%
of population, 2024
Homicide rate
5.8
per 100k, 2023
Road deaths
12.7
per 100k/yr, 2019
Income group
High
World Bank
Religion
Protestant 47%unaffiliated 23%Roman Catholic 21%Jewish 2%

Sources: World Bank, US State Department, World Happiness Report, WHO/UNICEF, EF EPI, CIA World Factbook.

Data sources

Temperature, precipitation, cloud, humidity, wind and solar figures are a 1991–2020 climatology for Dover (39.1582°, -75.5244°, elevation 30 ft), computed from hourly ERA5 reanalysis — contains modified Copernicus Climate Change Service information. Sun figures are astronomical calculations, not observations. City data © GeoNames, CC BY 4.0. Map outlines from Natural Earth (public domain); interactive map © Google. Tropical-cyclone seasons are the published climatological basin seasons (NOAA National Hurricane Center / regional warning centres). Sea temperatures are the NOAA OISST v2.1 1991–2020 monthly climatology (public domain), sampled at the nearest ocean point. UV index is derived from CAMS (Copernicus Atmosphere Monitoring Service) clear-sky UV data — contains modified Copernicus Atmosphere Monitoring Service information. Monthly air-quality (PM2.5) seasonality is from the CAMS EAC4 reanalysis (Copernicus Atmosphere Monitoring Service), scaled to the WHO annual mean where available. Topography is sampled from the Copernicus DEM GLO-90 elevation model (© ESA/Airbus) and ESA WorldCover 2021 land cover (CC BY 4.0).