Chester weather in September

In September, Chester sees average daytime highs of 78°F and overnight lows near 61°F, with 3.9 in of rain across 9.1 wet days and about 12.3 hours of daylight. It is the 4th-warmest and 2nd-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 37% 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 Chester's 2nd-clearest and 10th-windiest month. For the whole year in context, see Chester's year-round climate.

Daytime high
78°
4th warmest
Overnight low
61°
9th coldest
Rainfall
3.9 in
9.1 wet days
Daylight
12 h 18 min
5:48 AM – 6:03 PM
Cloud cover
55%
2nd clearest
Wind
6 mph
10th windiest
Solar energy
4.29 kWh/m²
Travel score
6.9
out of 10

Chester is city in Delaware County, Pennsylvania, United States.

Density
2,192/km²
people per km²
Founded
1682

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 Chester reaches about 78°F in the afternoon and slips back to 61°F overnight — a 17°F spread between the day's warmth and the night's chill. On most days the high lands between 69°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)
18266
28265
38265
48165
58165
68164
78064
88064
98064
108063
117963
127962
137862
147862
157861
167861
177760
187760
197660
207660
217659
227559
237558
247558
257458
267457
277457
287357
297356
307356

How September really feels in Chester

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.

Chester weather by month

How September compares with the rest of the year at a glance. September is the 4th-warmest and 2nd-wettest month here — the current month is highlighted below.

MonthHigh / Low (°F)Rainfall (inches)Wet daysSnow daysDaylight (hours)Travel score
Jan41° / 28°3.19.23.49.50.1
Feb44° / 29°2.98.73.110.40.8
Mar53° / 36°4.010.7211.72.8
Apr64° / 46°3.410.20.3135.5
May73° / 55°3.310.3014.26.6
Jun82° / 65°3.710.2014.86.0
Jul86° / 70°3.610.7014.55.0
Aug84° / 68°3.810.3013.65.6
Sep78° / 61°3.99.1012.36.9
Oct66° / 50°3.67.8010.96.4
Nov55° / 39°2.980.29.83.8
Dec46° / 32°3.88.91.89.21.3

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 37% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 15% of September, with mostly cloudy or overcast conditions the remaining 48%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
15545
25545
35446
45446
55446
65446
75446
85446
95446
105545
115545
125545
135446
145347
155347
165248
175248
185248
195149
205050
215050
225050
235050
245050
255050
265050
275050
285149
295149
305248

Chance of precipitation in September

Any precipitation

Chester gets around 3.9 in of rain over 9.1 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 (%)
127
228
328
428
528
629
729
829
929
1029
1129
1229
1328
1428
1528
1628
1729
1829
1929
2030
2130
2230
2331
2431
2531
2631
2731
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 34% of days. Sticky, muggy-or-worse air turns up on roughly 26% of them.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)
11719242516
21819232416
31819232416
42020222315
52120222215
62220222115
72320222114
82420222014
92620221913
102720221912
112820221812
123020221811
133120221810
14322022179
15341922178
16351922167
17361922167
18371922166
19382021155
20392021155
21412021154
22422020154
23432019143
24442019143
25462018142
26472017132
27482017132
28501916132
29511916122
30521915122

Wind in September

Winds average 6 mph in September.

Across September, daily wind ranges from about 6 mph on the calmest days to 7 mph at its breeziest. It stays fairly steady from day to day.

0246810151015202530
Wind speed (mph)Feels
16calm
26calm
36calm
46calm
56calm
66calm
76calm
86calm
96calm
106calm
116calm
126calm
136calm
146calm
156calm
166calm
176calm
186calm
196calm
206calm
216calm
226calm
236calm
246calm
256calm
267calm
277calm
287calm
297calm
307calm

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 5:34 AM to 6:02 AM, and sunset from 6:29 PM to 5:40 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.95:346:29
212.95:346:27
312.85:356:25
412.85:366:24
512.75:376:22
612.75:386:20
712.75:396:19
812.65:406:17
912.65:416:15
1012.55:426:14
1112.55:436:12
1212.45:446:10
1312.45:456:09
1412.35:466:07
1512.35:476:05
1612.35:486:03
1712.25:496:02
1812.25:506:00
1912.15:515:58
2012.15:525:57
2112.05:535:55
2212.05:545:53
2311.95:555:51
2411.95:565:50
2511.95:575:48
2611.85:585:46
2711.85:595:45
2811.76:005:43
2911.76:015:41
3011.66:025:40

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 4.29 kWh/m².

For context, solar energy here swings from a low near 1.86 kWh/m² to a high of 6.1 kWh/m² in June across the year — September's 4.29 kWh/m² falls in the middle.

024151015202530
Solar energy (kWh/m²)Level
14.9Bright
24.8Bright
34.8Bright
44.8Bright
54.7Bright
64.7Bright
74.6Bright
84.6Bright
94.6Bright
104.5Bright
114.5Bright
124.5Bright
134.4Bright
144.4Bright
154.3Bright
164.3Bright
174.3Bright
184.2Bright
194.2Bright
204.1Bright
214.1Bright
224.0Bright
234.0Bright
244.0Moderate
253.9Moderate
263.9Moderate
273.9Moderate
283.8Moderate
293.8Moderate
303.8Moderate
Planning a trip in September

Hazard calendar for Chester

In seasonPeak

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

Chester 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 Chester?

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

6.9
Sightseeing
1st-best month of the year
6.3
Beach & pool
4th-best month of the year

September is a reasonable time to visit Chester for sightseeing. The water and warmth also suit a beach or pool day.

What to pack for Chester in September

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

In September, Chester sees daytime highs around 78°F and nights near 61°F. Worth packing: light clothes and rain gear. About 9 days see rain.

light clothesrain gear

UV index in Chester 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 Chester peaks around July 10 at about 8 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near December 21 at about 2 (low).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 8 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecModerateHighVery highHighModerateLowJul 10UV 8Dec 21UV 2
UV index (midday)Level
Jan2Low
Feb3Moderate
Mar5Moderate
Apr6High
May8Very high
Jun8Very high
Jul8Very high
Aug6High
Sep6High
Oct3Moderate
Nov3Moderate
Dec2Low

Air quality in Chester 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 Chester is worst in July — around 18 µg/m³ PM2.5 (moderate), about 2.0× the cleanest month (November, 9 µg/m³).

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

01020JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodJul 1317 µg/m³Nov 129 µg/m³
PM2.5 (µg/m³)Level
Jan11Good
Feb13Moderate
Mar15Moderate
Apr13Moderate
May15Moderate
Jun16Moderate
Jul18Moderate
Aug15Moderate
Sep12Good
Oct9Good
Nov9Good
Dec10Good
Location & terrain

Where is Chester?

Chester sits at 39.8°N, 75.4°W, 13 ft above sea level, in United States. The nearest listed city is Springfield, 6.2 mi away.

Topography around Chester

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

Within 2 miles, the terrain around Chester has only modest variations in elevation — a maximum elevation change of 171 ft around an average of 33 ft above sea level; within 10 miles, only modest variations in elevation — a maximum elevation change of 725 ft; within 50 miles, significant variations in elevation — a maximum elevation change of 1,516 ft.

The land around Chester is covered by artificial surfaces (32%), water (32%) and trees (24%) within 2 miles, trees (51%) within 10 miles, and trees (58%) within 50 miles.

2 miles
171 ft
10 miles
725 ft
50 miles
1,516 ft
treesgrasslandcroplandartificial surfacesbare terrainwaterwetland
September weather nearby: Springfield 6.2 mi · Drexel Hill 7.5 mi · Elmwood 8.7 mi · Kingsessing 9.3 mi · Cobbs Creek 9.3 mi · Havertown 9.3 mi · Haddington 11 mi · University City 11 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 Chester (39.8475°, -75.3578°, elevation 13 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). 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).