King of Prussia weather in September

In September, King of Prussia sees average daytime highs of 77°F and overnight lows near 60°F, with 4.5 in of rain across 9.6 wet days and about 12.3 hours of daylight. It is the 4th-warmest and 1st-wettest month of the year here.

Highs ease over the month, from about 81°F in the first days to 72°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 King of Prussia's 2nd-clearest and 9th-windiest month. For the whole year in context, see King of Prussia's year-round climate.

Daytime high
77°
4th warmest
Overnight low
60°
9th coldest
Rainfall
4.5 in
9.6 wet days
Daylight
12 h 18 min
5:48 AM – 6:04 PM
Cloud cover
55%
2nd clearest
Wind
6 mph
9th windiest
Solar energy
4.25 kWh/m²
Travel score
6.9
out of 10

King of Prussia is census-designated place in Montgomery County, Pennsylvania, United States.

Density
891/km²
people per km²
Founded
1719

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 72°F by the end.

A typical September day in King of Prussia reaches about 77°F in the afternoon and slips back to 60°F overnight — a 17°F spread between the day's warmth and the night's chill. On most days the high lands between 68°F and 85°F. Set against its neighbours, September runs about 7°F cooler than August and about 12°F warmer than October.

40°60°80°151015202530
Avg high (°F)Avg low (°F)
18165
28165
38164
48164
58064
68064
78063
87963
97962
107962
117862
127861
137861
147761
157760
167760
177659
187659
197659
207558
217558
227458
237457
247457
257356
267356
277356
287255
297255
307155

How September really feels in King of Prussia

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.

King of Prussia weather by month

How September compares with the rest of the year at a glance. September is the 4th-warmest and 1st-wettest month here — the current month is highlighted below.

MonthHigh / Low (°F)Rainfall (inches)Wet daysSnow daysDaylight (hours)Travel score
Jan40° / 27°3.39.43.99.50.0
Feb43° / 28°3.09.23.510.40.4
Mar51° / 35°4.110.72.811.72.5
Apr63° / 45°3.810.80.3135.2
May72° / 54°3.711.4014.26.4
Jun81° / 64°4.211.3014.86.0
Jul85° / 69°4.211.4014.65.0
Aug83° / 67°3.910.5013.65.7
Sep77° / 60°4.59.6012.36.9
Oct65° / 49°3.78.50.110.96.1
Nov54° / 39°3.080.39.83.4
Dec44° / 31°4.09.429.20.8

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 (%)
15248
25347
35347
45248
55347
65347
75347
85347
95248
105347
115347
125347
135347
145248
155248
165149
175149
185050
195149
204951
214951
224951
235050
245050
255050
265050
275050
285050
295248
305248

Chance of precipitation in September

Any precipitation

King of Prussia gets around 4.5 in of rain over 9.6 wet days in September, the wettest month. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 31% and peaks near 33% on the wettest days.

0%10%20%30%40%151015202530
Rain chance (%)
128
228
329
429
529
629
730
830
930
1030
1130
1230
1330
1430
1530
1630
1730
1831
1931
2032
2132
2233
2333
2433
2533
2633
2733
2833
2933
3033

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 39% of days. Sticky, muggy-or-worse air turns up on roughly 21% of them.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)
12222222213
22222222113
32322222112
42422212012
52622211912
62722211911
72822211811
82922211810
93022211710
10312121179
11332121168
12342122168
13352022167
14372022156
15382022155
16392022145
17402022144
18422021144
19432021133
20442021133
21452020133
22462019122
23482019122
24492018112
25512017111
26512017111
27541916101
28541916101
29561815101
30561815101

Wind in September

Winds average 6 mph in September.

Across September, daily wind ranges from about 6 mph on the calmest days to 6 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
266calm
276calm
286calm
296calm
306calm

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 5:33 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)
112.95:336:29
212.95:346:28
312.85:356:26
412.85:366:24
512.85:376:23
612.75:386:21
712.75:396:19
812.65:406:17
912.65:416:16
1012.55:426:14
1112.55:436:12
1212.45:446:11
1312.45:456:09
1412.45:466:07
1512.35:476:05
1612.35:486:04
1712.25:496:02
1812.25:506:00
1912.15:515:59
2012.15:525:57
2112.05:535:55
2212.05:545:53
2311.95:555:52
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 4.25 kWh/m².

For context, solar energy here swings from a low near 1.81 kWh/m² to a high of 6.06 kWh/m² in June across the year — September's 4.25 kWh/m² falls in the middle.

024151015202530
Solar energy (kWh/m²)Level
14.8Bright
24.8Bright
34.8Bright
44.7Bright
54.7Bright
64.6Bright
74.6Bright
84.6Bright
94.5Bright
104.5Bright
114.5Bright
124.4Bright
134.4Bright
144.3Bright
154.3Bright
164.3Bright
174.2Bright
184.2Bright
194.1Bright
204.1Bright
214.1Bright
224.0Bright
234.0Moderate
243.9Moderate
253.9Moderate
263.9Moderate
273.8Moderate
283.8Moderate
293.8Moderate
303.7Moderate
Planning a trip in September

Is September a good time to visit King of Prussia?

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
6.1
Beach & pool
4th-best month of the year

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

What to pack for King of Prussia in September

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

In September, King of Prussia sees daytime highs around 77°F and nights near 60°F. Worth packing: light clothes and rain gear. About 10 days see rain.

light clothesrain gear

UV index in King of Prussia 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 King of Prussia 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 King of Prussia 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 King of Prussia is worst in July — around 17 µg/m³ PM2.5 (moderate), about 2.0× the cleanest month (November, 8 µg/m³).

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

01020JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodJul 1317 µg/m³Nov 128 µg/m³
PM2.5 (µg/m³)Level
Jan10Good
Feb12Good
Mar13Moderate
Apr13Moderate
May15Moderate
Jun16Moderate
Jul17Moderate
Aug14Moderate
Sep12Good
Oct9Good
Nov8Good
Dec9Good
Location & terrain

Where is King of Prussia?

King of Prussia sits at 40.1°N, 75.4°W, 200 ft above sea level, in United States. The nearest listed city is Wayne, 3.1 mi away.

Topography around King of Prussia

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

Within 2 miles, the terrain around King of Prussia has only modest variations in elevation — a maximum elevation change of 512 ft around an average of 210 ft above sea level; within 10 miles, significant variations in elevation — a maximum elevation change of 1,004 ft; within 50 miles, significant variations in elevation — a maximum elevation change of 1,936 ft.

The land around King of Prussia is covered by trees (56%) and artificial surfaces (27%) within 2 miles, trees (68%) within 10 miles, and trees (58%) within 50 miles.

2 miles
512 ft
10 miles
1,004 ft
50 miles
1,936 ft
treesgrasslandcroplandartificial surfaceswaterwetland
September weather nearby: Wayne 3.1 mi · Radnor 3.7 mi · Norristown 3.7 mi · Phoenixville 6.8 mi · Havertown 8.7 mi · Overbrook 11 mi · East Mount Airy 11 mi · Drexel Hill 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 King of Prussia (40.0893°, -75.396°, elevation 200 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. 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).