Allentown weather in May

In May, Allentown sees average daytime highs of 71°F and overnight lows near 52°F, with 3.7 in of rain across 11.5 wet days and about 14.2 hours of daylight. It is the 5th-warmest and 8th-wettest month of the year here.

Highs climb over the month, from about 67°F in the first days to 76°F by the end. The sky is clear or mostly clear about 24% of the time in May, and the air most often feels dry.

Daylight stretches from about 13 h 42 min at the start of May to 14 h 42 min by month's end. Set against the rest of the year, May is Allentown's 11th-clearest and 8th-windiest month. For the whole year in context, see Allentown's year-round climate.

Daytime high
71°
5th warmest
Overnight low
52°
8th coldest
Rainfall
3.7 in
11.5 wet days
Daylight
14 h 18 min
4:51 AM – 7:06 PM
Cloud cover
64%
11th clearest
Wind
6 mph
8th windiest
Solar energy
5.63 kWh/m²
Travel score
6.3
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 May

Average highAverage lowShaded bands: 10–90% of days

Highs climb over the month, from about 67°F in the first days to 76°F by the end.

A typical May day in Allentown reaches about 71°F in the afternoon and slips back to 52°F overnight — a 19°F spread between the day's warmth and the night's chill. On most days the high lands between 59°F and 84°F. Set against its neighbours, May runs about 10°F warmer than April and about 9°F cooler than June.

40°60°80°151015202531
Avg high (°F)Avg low (°F)
16747
26748
36748
46749
56849
66849
76849
86950
96950
106950
116951
127051
137051
147051
157152
167152
177152
187253
197253
207253
217354
227354
237454
247455
257455
267555
277556
287656
297656
307657
317657

How May really feels in Allentown

Once humidity and wind are folded in, May 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

May sits comfortably in between — no days that feel dangerously hot or drop to a hard freeze once humidity and wind are folded in.

Allentown weather by month

How May compares with the rest of the year at a glance. May is the 5th-warmest and 8th-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 May

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 24% of the time in May.

Beyond those clear spells, partly cloudy skies cover about 19% of May, with mostly cloudy or overcast conditions the remaining 58%.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
14258
24258
34357
44357
54357
64357
74357
84258
94357
104357
114357
124357
134258
144258
154159
164258
174258
184258
194159
204159
214159
224159
234357
244357
254357
264357
274258
284357
294357
304258
314357

Chance of precipitation in May

Any precipitation

Allentown gets around 3.7 in of rain over 11.5 wet days in May. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 37% and peaks near 38% on the wettest days.

0%10%20%30%40%50%151015202531
Rain chance (%)
134
234
335
435
535
636
736
836
937
1037
1137
1237
1337
1437
1537
1637
1737
1837
1937
2038
2138
2238
2338
2438
2538
2638
2738
2838
2937
3037
3137

Humidity in May

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, May lands in the dry band about 70% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202531
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)
18710300
28511400
38511400
48312500
58312500
68113600
78113600
87914700
97914700
107814800
117614910
127614910
1374151010
1474151010
1572151120
1672151120
1770161220
1869161230
1967171240
2066171340
2163181450
2262181460
2361181560
2459191570
2558191670
2656201680
2756201680
2854201790
2953211790
3051211891
31502118101

Wind in May

Winds average 6 mph in May.

Across May, 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.

0246810151015202531
Wind speed (mph)Feels
17calm
27calm
37calm
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
316calm

Sunrise & sunset in May

DaylightNight

Daylight runs from about 13 h 42 min at the start of May to 14 h 42 min by month's end. The lit band spans sunrise to sunset each day.

Days grow by about 60 minutes over May. Sunrise moves from 5:08 AM to 4:40 AM, and sunset from 6:50 PM to 7:19 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
113.75:086:50
213.75:076:51
313.85:056:53
413.85:046:54
513.95:036:55
613.95:026:56
713.95:006:57
814.04:596:58
914.04:586:59
1014.04:577:00
1114.14:567:01
1214.14:557:02
1314.24:547:03
1414.24:537:04
1514.24:527:05
1614.34:517:06
1714.34:507:07
1814.34:497:08
1914.34:487:09
2014.44:477:10
2114.44:467:11
2214.44:457:11
2314.54:457:12
2414.54:447:13
2514.54:437:14
2614.54:427:15
2714.64:427:16
2814.64:417:17
2914.64:417:18
3014.64:407:18
3114.74:407:19

Solar energy in May

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in May, about 5.63 kWh/m².

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 — May's 5.63 kWh/m² sits near the top of that range.

0246151015202531
Solar energy (kWh/m²)Level
15.3Bright
25.4Bright
35.4Bright
45.4Bright
55.4Bright
65.4Bright
75.5Bright
85.5Bright
95.5Bright
105.5Bright
115.5Bright
125.5Bright
135.6Bright
145.6Bright
155.6Bright
165.6Bright
175.6Bright
185.7Bright
195.7Bright
205.7Bright
215.7Bright
225.7Bright
235.8Bright
245.8Bright
255.8Bright
265.8Bright
275.8Bright
285.9Bright
295.9Bright
305.9Bright
315.9Bright
Planning a trip in May

Is May a good time to visit Allentown?

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

6.3
Sightseeing
2nd-best month of the year
4.3
Beach & pool
5th-best month of the year

May is a reasonable time to visit Allentown for sightseeing.

What to pack for Allentown in May

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

In May, Allentown sees daytime highs around 71°F and nights near 52°F. Worth packing: rain gear and sun protection. About 12 days see rain.

rain gearsun protection

UV index in Allentown in May

LowModerateHighVery highExtreme

Clear-sky midday UV in May peaks around 8 — enough to warrant sun protection. 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 May

GoodModeratePoorUnhealthyVery unhealthy

Average fine-particle pollution (PM2.5) through the year — so you can see where May 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
May 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).