Upper Saint Clair weather in September

In September, Upper Saint Clair sees average daytime highs of 75°F and overnight lows near 56°F, with 3.9 in of rain across 10 wet days and about 12.3 hours of daylight. It is the 4th-warmest and 6th-wettest month of the year here.

Highs ease over the month, from about 79°F in the first days to 70°F by the end. The sky is clear or mostly clear about 34% 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 Upper Saint Clair's 1st-clearest and 10th-windiest month. For the whole year in context, see Upper Saint Clair's year-round climate.

Daytime high
75°
4th warmest
Overnight low
56°
9th coldest
Rainfall
3.9 in
10 wet days
Daylight
12 h 18 min
6:07 AM – 6:23 PM
Cloud cover
56%
1st clearest
Wind
6 mph
10th windiest
Solar energy
4.22 kWh/m²
Travel score
6.8
out of 10

Upper Saint Clair is home rule municipality in Allegheny County, Pennsylvania, United States.

Founded
1830

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 79°F in the first days to 70°F by the end.

A typical September day in Upper Saint Clair reaches about 75°F in the afternoon and slips back to 56°F overnight — a 19°F spread between the day's warmth and the night's chill. On most days the high lands between 65°F and 85°F. Set against its neighbours, September runs about 6°F cooler than August and about 12°F warmer than October.

40°60°80°151015202530
Avg high (°F)Avg low (°F)
17961
27961
37960
47960
57860
67860
77859
87859
97759
107758
117758
127658
137657
147657
157556
167556
177456
187455
197455
207355
217354
227354
237254
247253
257253
267153
277152
287052
297051
307051

How September really feels in Upper Saint Clair

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.

Upper Saint Clair weather by month

How September compares with the rest of the year at a glance. September is the 4th-warmest and 6th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°F)Rainfall (inches)Wet daysSnow daysDaylight (hours)Travel score
Jan37° / 24°3.612.26.89.50.0
Feb41° / 25°3.211.15.510.40.2
Mar50° / 33°4.4133.511.72.1
Apr62° / 43°4.613.80.9134.7
May71° / 52°5.014.4014.25.8
Jun79° / 61°5.213.9014.86.0
Jul82° / 65°5.014.4014.65.6
Aug81° / 63°3.812.2013.66.2
Sep75° / 56°3.910012.36.8
Oct63° / 45°3.610.40.210.95.4
Nov51° / 36°3.5101.29.82.5
Dec42° / 29°3.511.44.29.20.2

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 34% of the time in September, the clearest month of the year.

Beyond those clear spells, partly cloudy skies cover about 18% of September, with mostly cloudy or overcast conditions the remaining 49%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
15644
25545
35545
45545
55545
65446
75446
85446
95347
105248
115248
125149
135149
145149
155050
165050
175050
184951
194951
205050
214951
224951
234951
244951
255050
265050
275050
285050
295050
305050

Chance of precipitation in September

Any precipitation

Upper Saint Clair gets around 3.9 in of rain over 10 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 33% and peaks near 35% on the wettest days.

0%10%20%30%40%50%151015202530
Rain chance (%)
132
232
331
431
531
631
731
831
932
1032
1132
1232
1332
1432
1532
1632
1733
1833
1933
2034
2134
2234
2334
2435
2535
2635
2735
2834
2934
3034

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 43% of days. Sticky, muggy-or-worse air turns up on roughly 14% of them.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)
1222424246
2242423246
3252423235
4262422225
5282522215
6292522205
7302522194
8322522184
9332522173
10342522163
11362522152
12372422142
13392422142
14402422132
15422322121
16432322111
17452321101
1847222191
1948222190
2051212080
2153211970
2253211970
2356201860
2457201760
2559191660
2660191650
2762181550
2863181450
2963181450
3066171340

Wind in September

Winds average 6 mph in September.

Across September, daily wind ranges from about 5 mph on the calmest days to 6 mph at its breeziest. It stays fairly steady from day to day.

0246810151015202530
Wind speed (mph)Feels
15calm
25calm
35calm
45calm
55calm
65calm
75calm
85calm
95calm
105calm
115calm
125calm
135calm
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 5:52 AM to 6:21 AM, and sunset from 6:48 PM to 5:58 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.95:526:48
212.95:536:46
312.85:546:45
412.85:556:43
512.85:566:41
612.75:576:40
712.75:586:38
812.65:596:36
912.66:006:35
1012.56:016:33
1112.56:026:31
1212.46:036:29
1312.46:046:28
1412.46:056:26
1512.36:066:24
1612.36:076:23
1712.26:086:21
1812.26:096:19
1912.16:106:17
2012.16:116:16
2112.06:126:14
2212.06:136:12
2311.96:146:10
2411.96:156:09
2511.96:166:07
2611.86:176:05
2711.86:186:03
2811.76:196:02
2911.76:206:00
3011.66:215:58

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 4.22 kWh/m².

For context, solar energy here swings from a low near 1.53 kWh/m² to a high of 5.94 kWh/m² in June across the year — September's 4.22 kWh/m² falls in the middle.

024151015202530
Solar energy (kWh/m²)Level
14.8Bright
24.8Bright
34.7Bright
44.7Bright
54.7Bright
64.6Bright
74.6Bright
84.5Bright
94.5Bright
104.5Bright
114.4Bright
124.4Bright
134.3Bright
144.3Bright
154.3Bright
164.2Bright
174.2Bright
184.1Bright
194.1Bright
204.0Bright
214.0Moderate
224.0Moderate
233.9Moderate
243.9Moderate
253.8Moderate
263.8Moderate
273.8Moderate
283.7Moderate
293.7Moderate
303.6Moderate
Planning a trip in September

Is September a good time to visit Upper Saint Clair?

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

6.8
Sightseeing
1st-best month of the year
5.6
Beach & pool
4th-best month of the year

September is a reasonable time to visit Upper Saint Clair for sightseeing.

What to pack for Upper Saint Clair in September

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

In September, Upper Saint Clair sees daytime highs around 75°F and nights near 56°F. Worth packing: light clothes and rain gear. About 10 days see rain.

light clothesrain gear

UV index in Upper Saint Clair 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 Upper Saint Clair peaks around June 22 at about 9 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near December 22 at about 2 (low).

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

025710JanFebMarAprMayJunJulAugSepOctNovDecLowModerateHighVery highHighModerateLowJun 22UV 9Dec 22UV 2
UV index (midday)Level
Jan2Low
Feb3Moderate
Mar5Moderate
Apr6High
May8Very high
Jun9Very high
Jul9Very high
Aug7Very high
Sep6High
Oct3Moderate
Nov2Moderate
Dec2Low

Air quality in Upper Saint Clair 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 Upper Saint Clair is worst in July — around 17 µg/m³ PM2.5 (moderate), about 2.3× the cleanest month (November, 7 µg/m³).

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

01020JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodJul 1317 µg/m³Nov 147 µg/m³
PM2.5 (µg/m³)Level
Jan9Good
Feb10Good
Mar11Good
Apr11Good
May15Moderate
Jun16Moderate
Jul17Moderate
Aug15Moderate
Sep12Good
Oct8Good
Nov7Good
Dec8Good
Location & terrain

Where is Upper Saint Clair?

Upper Saint Clair sits at 40.3°N, 80.1°W, 1,099 ft above sea level, in United States. The nearest listed city is Mount Lebanon, 2.5 mi away.

Topography around Upper Saint Clair

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

Within 2 miles, the terrain around Upper Saint Clair has only modest variations in elevation — a maximum elevation change of 453 ft around an average of 1,070 ft above sea level; within 10 miles, only modest variations in elevation — a maximum elevation change of 722 ft; within 50 miles, large variations in elevation — a maximum elevation change of 2,359 ft.

The land around Upper Saint Clair is covered by trees (72%) within 2 miles, trees (66%) within 10 miles, and trees (76%) within 50 miles.

2 miles
453 ft
10 miles
722 ft
50 miles
2,359 ft
treesgrasslandcroplandartificial surfaceswater
September weather nearby: Mount Lebanon 2.5 mi · Bethel Park 2.5 mi · Baldwin 5.6 mi · Pittsburgh 8.7 mi · McKeesport 12 mi · West Mifflin 12 mi · Wilkinsburg 13 mi · Monroeville 17 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 Upper Saint Clair (40.3359°, -80.0834°, elevation 1,099 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).