Lebanon weather in September

In September, Lebanon sees average daytime highs of 76°F and overnight lows near 59°F, with 4.3 in of rain across 9.4 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 36% 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 Lebanon's 2nd-clearest and 9th-windiest month. For the whole year in context, see Lebanon's year-round climate.

Daytime high
76°
4th warmest
Overnight low
59°
9th coldest
Rainfall
4.3 in
9.4 wet days
Daylight
12 h 18 min
5:52 AM – 6:08 PM
Cloud cover
56%
2nd clearest
Wind
6 mph
9th windiest
Solar energy
4.23 kWh/m²
Travel score
6.9
out of 10

Lebanon is county seat of Lebanon County, Pennsylvania, United States.

Density
2,366/km²
people per km²
Founded
1720

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 Lebanon reaches about 76°F in the afternoon and slips back to 59°F overnight — a 17°F spread between the day's warmth and the night's chill. On most days the high lands between 67°F and 86°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)
18164
28163
38163
48063
58063
68062
78062
87962
97961
107861
117861
127860
137760
147759
157759
167659
177658
187658
197558
207557
217457
227456
237456
247356
257355
267355
277255
287254
297154
307153

How September really feels in Lebanon

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.

Lebanon 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
Jan38° / 25°3.49.34.49.50.0
Feb41° / 26°3.08.9410.40.2
Mar50° / 33°3.910.53.211.72.3
Apr62° / 44°3.810.80.4135.1
May72° / 54°3.611.9014.26.3
Jun81° / 63°3.611.3014.86.0
Jul85° / 68°3.610.2014.65.2
Aug83° / 66°3.210013.65.8
Sep76° / 59°4.39.4012.36.9
Oct64° / 47°3.78.70.110.95.9
Nov53° / 37°3.28.40.79.83.0
Dec43° / 30°3.79.32.99.20.5

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 36% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 17% of September, with mostly cloudy or overcast conditions the remaining 47%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
15248
25347
35347
45248
55347
65347
75347
85347
95347
105347
115347
125347
135248
145347
155347
165248
175248
185347
195248
205248
215248
225248
235248
245347
255347
265347
275347
285446
295446
305446

Chance of precipitation in September

Any precipitation

Lebanon gets around 4.3 in of rain over 9.4 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 30% and peaks near 33% on the wettest days.

0%10%20%30%40%151015202530
Rain chance (%)
129
229
329
429
529
629
729
829
929
1028
1128
1228
1328
1428
1528
1628
1729
1829
1930
2031
2131
2232
2332
2433
2533
2633
2733
2833
2933
3032

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 44% of days. Sticky, muggy-or-worse air turns up on roughly 17% of them.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)
1252719236
2262719235
3272719225
4282718215
5292718215
6312718205
7322618195
8342618194
9352518184
10362518184
11382418173
12392418163
13412318163
14422218152
15442218142
16452118142
17462118132
18482018121
19492018121
20502018111
21512018101
22531917101
2354191791
2455191790
2557191680
2658181680
2759181670
2860181570
2962171560
3062171560

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
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 5:37 AM to 6:06 AM, and sunset from 6:33 PM to 5:44 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.95:376:33
212.95:386:32
312.85:396:30
412.85:406:28
512.85:416:27
612.75:426:25
712.75:436:23
812.65:446:22
912.65:456:20
1012.55:466:18
1112.55:476:17
1212.45:486:15
1312.45:496:13
1412.45:506:11
1512.35:516:10
1612.35:526:08
1712.25:536:06
1812.25:546:04
1912.15:556:03
2012.15:566:01
2112.05:575:59
2212.05:585:57
2311.95:595:56
2411.96:005:54
2511.96:015:52
2611.86:025:50
2711.86:035:49
2811.76:045:47
2911.76:055:45
3011.66:065:44

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 4.23 kWh/m².

For context, solar energy here swings from a low near 1.76 kWh/m² to a high of 6.09 kWh/m² in June across the year — September's 4.23 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
184.2Bright
194.1Bright
204.1Bright
214.0Bright
224.0Moderate
234.0Moderate
243.9Moderate
253.9Moderate
263.8Moderate
273.8Moderate
283.8Moderate
293.7Moderate
303.7Moderate
Planning a trip in September

Is September a good time to visit Lebanon?

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
6.0
Beach & pool
4th-best month of the year

September is a reasonable time to visit Lebanon for sightseeing.

What to pack for Lebanon in September

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

In September, Lebanon sees daytime highs around 76°F and nights near 59°F. Worth packing: light clothes and rain gear. About 9 days see rain.

light clothesrain gear

UV index in Lebanon 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 Lebanon peaks around June 22 at about 8 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near December 21 at about 1 (low).

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

025710JanFebMarAprMayJunJulAugSepOctNovDecModerateHighVery highHighModerateLowJun 22UV 8Dec 21UV 1
UV index (midday)Level
Jan2Low
Feb3Moderate
Mar5Moderate
Apr6High
May8Very high
Jun9Very high
Jul8Very high
Aug6High
Sep6High
Oct3Moderate
Nov2Moderate
Dec1Low

Air quality in Lebanon 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 Lebanon is worst in July — around 17 µg/m³ PM2.5 (moderate), about 2.1× the cleanest month (November, 8 µg/m³).

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

01020JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodJul 1317 µg/m³Nov 138 µg/m³
PM2.5 (µg/m³)Level
Jan10Good
Feb12Good
Mar13Moderate
Apr14Moderate
May15Moderate
Jun16Moderate
Jul17Moderate
Aug15Moderate
Sep12Good
Oct9Good
Nov8Good
Dec9Good
Location & terrain

Where is Lebanon?

Lebanon sits at 40.3°N, 76.4°W, 469 ft above sea level, in United States. The nearest listed city is Lancaster, 22 mi away.

Topography around Lebanon

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

Within 2 miles, the terrain around Lebanon has only modest variations in elevation — a maximum elevation change of 256 ft around an average of 525 ft above sea level; within 10 miles, significant variations in elevation — a maximum elevation change of 1,201 ft; within 50 miles, large variations in elevation — a maximum elevation change of 2,178 ft.

The land around Lebanon is covered by trees (32%), grassland (27%) and artificial surfaces (27%) within 2 miles, trees (36%), cropland (36%) and grassland (23%) within 10 miles, and trees (58%) and cropland (21%) within 50 miles.

2 miles
256 ft
10 miles
1,201 ft
50 miles
2,178 ft
treesgrasslandcroplandartificial surfaceswater
September weather nearby: Lancaster 22 mi · Harrisburg 25 mi · Reading 25 mi · York 31 mi · Pottstown 40 mi · Carlisle 42 mi · Limerick 47 mi · Hanover 48 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 Lebanon (40.3409°, -76.4113°, elevation 469 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).