Allentown weather in December

In December, Allentown sees average daytime highs of 42°F and overnight lows near 29°F, with 4.0 in of precipitation across 9.4 wet days and about 9.1 hours of daylight. It is the 10th-warmest and 4th-wettest month of the year here.

Highs ease over the month, from about 46°F in the first days to 40°F by the end. The sky is clear or mostly clear about 28% of the time in December, and the air most often feels dry.

Daylight stretches from about 9 h 18 min at the start of December to 9 h 06 min by month's end. Set against the rest of the year, December is Allentown's 7th-clearest and 5th-windiest month. For the whole year in context, see Allentown's year-round climate.

Daytime high
42°
10th warmest
Overnight low
29°
3rd coldest
Precipitation
4.0 in
9.4 wet days
Daylight
9 h 06 min
7:25 AM – 4:31 PM
Cloud cover
63%
7th clearest
Wind
7 mph
5th windiest
Solar energy
1.76 kWh/m²
Travel score
0.4
out of 10

Allentown is city in and seat of Lehigh County, Pennsylvania, United States.

Density
2,575/km²
people per km²
Founded
1762

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

Temperature in December

Average highAverage lowShaded bands: 10–90% of days

Highs ease over the month, from about 46°F in the first days to 40°F by the end.

A typical December day in Allentown reaches about 42°F in the afternoon and slips back to 29°F overnight — a 13°F spread between the day's warmth and the night's chill. On most days the high lands between 31°F and 55°F. Set against its neighbours, December runs about 10°F cooler than November and about 5°F warmer than January.

20°40°60°151015202531
Avg high (°F)Avg low (°F)
14733
24632
34632
44632
54531
64531
74431
84431
94430
104330
114330
124330
134229
144229
154229
164229
174229
184229
194228
204128
214128
224128
234128
244128
254128
264027
274027
284027
294027
304027
314027

How December really feels in Allentown

Once humidity and wind are folded in, December averages 0 days that feel above 90°F and 31 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
31
wind chill below the day's low

The story in December is cold — wind chill drags the overnight "feels like" below the raw low.

Allentown weather by month

How December compares with the rest of the year at a glance. December is the 10th-warmest and 4th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°F)Rainfall (inches)Wet daysSnow daysDaylight (hours)Travel score
Jan38° / 24°3.49.54.89.40.0
Feb41° / 25°3.08.9410.40.2
Mar49° / 32°4.0113.511.72.1
Apr62° / 43°3.910.60.4135.0
May71° / 52°3.711.5014.26.3
Jun81° / 62°4.111.4014.86.0
Jul85° / 67°3.811.2014.65.0
Aug83° / 65°3.710.1013.65.8
Sep76° / 58°4.48.8012.37.0
Oct64° / 46°3.98.90.110.95.8
Nov52° / 36°3.28.10.69.73.0
Dec42° / 29°4.09.42.99.10.4

Cloud cover in December

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 28% of the time in December.

Beyond those clear spells, partly cloudy skies cover about 14% of December, with mostly cloudy or overcast conditions the remaining 58%.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
14357
24258
34258
44060
54060
64060
73961
83961
93961
103961
113961
124060
134060
144060
154060
164159
174258
184258
194357
204456
214456
224555
234654
244753
254753
264753
274753
284654
294654
304555
314555

Chance of precipitation in December

Any precipitationSnow

Allentown gets around 4.0 in of rain and snow over 9.4 wet days in December. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable precipitation averages around 30% and peaks near 32% on the wettest days, and about 3 days bring snow.

0%10%20%30%40%151015202531
Rain chance (%)Snow chance (%)
1306
2307
3307
4308
5318
6318
7319
8329
93210
103210
113211
123211
133211
143211
153211
163210
173110
183110
193110
203010
213010
22299
23299
24299
25289
26289
27289
282910
292910
302911
312911

Humidity in December

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, December lands in the dry band about 99% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202531
Dry (%)Comfortable (%)
1982
2991
3991
4991
5991
6991
7991
8991
9991
10991
11991
12991
13991
14991
15991
16991
17991
18991
19991
20991
21991
22991
23991
24991
25991
26991
27991
28991
291000
301000
311000

Wind in December

Winds average 7 mph in December.

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

0246810151015202531
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
277calm
287calm
297calm
307calm
317calm

Sunrise & sunset in December

DaylightNight

Daylight runs from about 9 h 18 min at the start of December to 9 h 06 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 12 minutes over December. Sunrise moves from 7:12 AM to 7:31 AM, and sunset from 4:31 PM to 4:39 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
19.37:124:31
29.37:134:31
39.37:144:31
49.37:154:30
59.27:164:30
69.27:174:30
79.27:184:30
89.27:194:30
99.27:204:30
109.27:214:30
119.27:214:30
129.17:224:31
139.17:234:31
149.17:244:31
159.17:244:31
169.17:254:31
179.17:254:32
189.17:264:32
199.17:274:32
209.17:274:33
219.17:284:33
229.17:284:34
239.17:294:34
249.17:294:35
259.17:294:35
269.17:304:36
279.17:304:36
289.17:304:37
299.17:314:38
309.17:314:38
319.17:314:39

Solar energy in December

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in December, about 1.76 kWh/m² — the year's lowest.

For context, solar energy here swings from a low near 1.76 kWh/m² to a high of 6.02 kWh/m² in June across the year — December's 1.76 kWh/m² sits near the bottom.

00.511.522.5151015202531
Solar energy (kWh/m²)Level
11.9Dim
21.9Dim
31.8Dim
41.8Dim
51.8Dim
61.8Dim
71.8Dim
81.8Dim
91.8Dim
101.7Dim
111.7Dim
121.7Dim
131.7Dim
141.7Dim
151.7Dim
161.7Dim
171.7Dim
181.7Dim
191.7Dim
201.7Dim
211.7Dim
221.8Dim
231.8Dim
241.8Dim
251.8Dim
261.8Dim
271.8Dim
281.8Dim
291.8Dim
301.8Dim
311.8Dim
Planning a trip in December

Is December a good time to visit Allentown?

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

0.4
Sightseeing
10th-best month of the year
0.0
Beach & pool
10th-best month of the year

December is a weaker month for outdoor sightseeing in Allentown.

What to pack for Allentown in December

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

In December, Allentown sees daytime highs around 42°F and nights near 29°F. Pack a warm layer. Worth having: a heavy coat and rain gear. About 9 days see rain.

a warm layera heavy coatrain gear

UV index in Allentown in December

LowModerateHighVery highExtreme

Clear-sky midday UV in December peaks around 1. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Allentown peaks around July 10 at about 8 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near December 22 at about 1 (low).

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

025710JanFebMarAprMayJunJulAugSepOctNovDecLowModerateHighVery highHighModerateLowJul 10UV 8Dec 22UV 1
UV index (midday)Level
Jan2Low
Feb3Moderate
Mar5Moderate
Apr6High
May8Very high
Jun8Very high
Jul8Very high
Aug6High
Sep6High
Oct3Moderate
Nov2Moderate
Dec1Low

Air quality in Allentown in December

GoodModeratePoorUnhealthyVery unhealthy

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

Air quality in Allentown 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 1417 µg/m³Nov 148 µg/m³
PM2.5 (µg/m³)Level
Jan10Good
Feb12Good
Mar13Moderate
Apr13Moderate
May16Moderate
Jun16Moderate
Jul17Moderate
Aug15Moderate
Sep12Good
Oct9Good
Nov8Good
Dec9Good
Location & terrain

Where is Allentown?

Allentown sits at 40.6°N, 75.5°W, 338 ft above sea level, in United States. The nearest listed city is Whitehall Township, 4.3 mi away.

Topography around Allentown

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

Within 2 miles, the terrain around Allentown has only modest variations in elevation — a maximum elevation change of 285 ft around an average of 344 ft above sea level; within 10 miles, significant variations in elevation — a maximum elevation change of 1,125 ft; within 50 miles, large variations in elevation — a maximum elevation change of 2,516 ft.

The land around Allentown is covered by trees (43%) and artificial surfaces (42%) within 2 miles, trees (47%) and grassland (22%) within 10 miles, and trees (71%) within 50 miles.

2 miles
285 ft
10 miles
1,125 ft
50 miles
2,516 ft
treesgrasslandcroplandartificial surfacesbare terrainwater
December weather nearby: Whitehall Township 4.3 mi · Bethlehem 6.2 mi · Easton 15 mi · Limerick 26 mi · Pottstown 27 mi · Lansdale 27 mi · Reading 30 mi · Phoenixville 33 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 Allentown (40.6084°, -75.4902°, elevation 338 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).