Allentown, Pennsylvania climate: Normal weather by month, frost dates and records
Allentown's normal year runs from 22°F January nights to 86°F July afternoons, with 47.4 inches of precipitation and 33 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 11.7°C, January lows of −6°C, July highs of 30°C, 1,203 mm of precipitation a year.
- NOAA stationAllentown Lehigh Valley International Airport
- Station IDUSW00014737
- Location40.65°N 75.45°W
- Elevation390 ft (119 m)
- From the center4 miles
- Population127,138
On October 22, the normal high in Allentown is 63°F and the normal low 42°F, and the chance of measurable rain or snow is 31%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Allentown.
- Jan 38° 22°
- Feb 42° 23°
- Mar 51° 31°
- Apr 63° 40°
- May 74° 51°
- Jun 82° 60°
- Jul 86° 65°
- Aug 84° 63°
- Sep 77° 55°
- Oct 66° 44°
- Nov 54° 34°
- Dec 43° 27°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
What is the weather like in Allentown each month?
July is the warmest month, with normal highs of 86°F; January the coldest, with normal lows of 22°F. The most precipitation falls in July (5.30 in), the least in February (2.77 in).
Each month has its own page with the day-by-day normals, the month's records and its recent years:
| Month | High | Low | Mean | Precip. | Snow | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | 38°F | 22°F | 30.1°F | 3.30 | 9.8 | 11 | <1 | 27 | 9 h 30 min |
| February | 42°F | 23°F | 32.4°F | 2.77 | 10.8 | 10 | <1 | 24 | 10 h 40 min |
| March | 51°F | 31°F | 40.7°F | 3.63 | 6.3 | 11 | <1 | 19 | 11 h 50 min |
| April | 63°F | 40°F | 51.8°F | 3.67 | 0.5 | 12 | <1 | 6 | 13 h 10 min |
| May | 74°F | 51°F | 62.0°F | 3.65 | 0.0 | 12 | 1 | <1 | 14 h 20 min |
| June | 82°F | 60°F | 70.9°F | 4.40 | 0.0 | 11 | 3 | <1 | 15 h |
| July | 86°F | 65°F | 75.6°F | 5.30 | 0.0 | 11 | 8 | <1 | 14 h 50 min |
| August | 84°F | 63°F | 73.6°F | 4.56 | 0.0 | 10 | 5 | <1 | 13 h 50 min |
| September | 77°F | 55°F | 66.3°F | 4.84 | 0.0 | 10 | 2 | <1 | 12 h 30 min |
| October | 66°F | 44°F | 54.6°F | 4.14 | 0.2 | 10 | <1 | 3 | 11 h 10 min |
| November | 54°F | 34°F | 43.9°F | 3.24 | 0.9 | 9 | <1 | 15 | 10 h |
| December | 43°F | 27°F | 35.0°F | 3.86 | 4.6 | 12 | <1 | 24 | 9 h 20 min |
| Year (annual) | 63°F | 43°F | 53.1°F | 47.36 | 33.1 | 129 | 18 | 118 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | 4°C | −6°C | −1.1°C | 84 mm | 25 cm |
| February | 5°C | −5°C | 0.2°C | 70 mm | 27 cm |
| March | 10°C | −1°C | 4.8°C | 92 mm | 16 cm |
| April | 17°C | 5°C | 11.0°C | 93 mm | 1 cm |
| May | 23°C | 10°C | 16.7°C | 93 mm | 0 cm |
| June | 28°C | 16°C | 21.6°C | 112 mm | 0 cm |
| July | 30°C | 18°C | 24.2°C | 135 mm | 0 cm |
| August | 29°C | 17°C | 23.1°C | 116 mm | 0 cm |
| September | 25°C | 13°C | 19.1°C | 123 mm | 0 cm |
| October | 19°C | 7°C | 12.6°C | 105 mm | 1 cm |
| November | 12°C | 1°C | 6.6°C | 82 mm | 2 cm |
| December | 6°C | −3°C | 1.7°C | 98 mm | 12 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USW00014737; annual normals. Wet days: 0.01 inch or more; 90°F days and freezing nights: NOAA's day counts. Daylight: sunrise to sunset on the 15th, computed from the latitude.
When is the best weather to visit Allentown?
Normal highs sit between 65°F and 85°F in May, June, August, September and October. Of those, September has the fewest days with rain (10).
That is a measurement, not a recommendation: it counts the months whose normal afternoon high sits between 65°F and 85°F, where a light layer is enough by day.
Source: NOAA NCEI 1991-2020 monthly normals, station USW00014737.
When is the last frost in Allentown?
In Allentown, the last spring frost (32°F) comes after April 20 in half of years and after May 6 in one year in ten; the first autumn frost comes before October 24 in half of years and before October 8 in one year in ten.
Frost-free in half of yearsFrost in 1 to 9 years out of 10Frost most years
- Last spring frost, half of years after
- April 201 year in 10 after May 6; 9 in 10 after April 6
- First autumn frost, half of years before
- October 241 year in 10 before October 8; 9 in 10 before November 6
NOAA puts the median frost-free season at 184 days, and the season without a hard freeze (28°F) at 211 days.
A hard freeze (28°F) comes after April 5 in half of springs and before November 4 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Allentown in zone 7a across its 4 ZIP code areas (7a in 18103, the largest). By the map's own method, the average of each year's coldest night over 1991-2020, Allentown's NOAA station is in zone 7a: the coldest night of a typical year reaches 2°F (30 complete years).
Frost dates for every NOAA station in Pennsylvania · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USW00014737; USDA 2023 Plant Hardiness Zone Map, ZIP listings: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed October 8, 2026; the station zone: ACIS daily lows, 1991-2020. A 10% date means one year in ten has a frost after it in spring or before it in autumn.
What hardiness zone is each Allentown ZIP code in?
The USDA's 2023 map gives each ZIP code area one zone. Allentown's 4 ZIP code areas are all in zone 7a. Each ZIP's frost dates are in the frost tool.
Source: USDA 2023 Plant Hardiness Zone Map, ZIP listings: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed October 8, 2026; ZIP areas in the place: Census Bureau 2020 ZCTA-to-place relationship file. A ZIP area counts when at least a tenth of its land (and 0.5 km²) lies in the place.
How hot and how cold does it get in Allentown?
In a normal year in Allentown, 18 days a year reach 90°F, 118 nights fall to 32°F or colder and 129 days bring measurable precipitation.
- Days at 90°F or more
- 18a normal year
- Days at 100°F or more
- fewer than 1a normal year
- Nights at 32°F or colder
- 118a normal year
- Days that stay below freezing
- 22high of 32°F or less
- Days with 0.01 inch of precipitation
- 129a normal year
- Days with 1 inch of snow or more
- 8a normal year
The highest temperature in Allentown's official record (kept by the National Weather Service since 1922) is 105°F, on July 3, 1966; the lowest is −15°F, on January 21, 1994.
The wettest calendar year on that record is 2011, with 71.72 in; the snowiest season is 1995–96, with 75.4 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USW00014737; records: ACIS (NOAA Regional Climate Centers), NWS threaded record ABEthr. Records use complete months only; a month missing more than three days is left out.
How humid and windy is Allentown, and how clear are its skies?
The summer (June-August) dew point averages 62°F. The muggiest month is July, with an average dew point of 63°F; the driest air comes in January (19°F). February is the windiest month (8.7 mph on average), and August has the most clear or nearly clear hours (63%).
| Month | Dew point | Humidity | Afternoon humidity | Wind | Clear or few clouds | Overcast |
|---|---|---|---|---|---|---|
| January | 19°F | 63% | 50% | 7.9 mph | 50% | 35% |
| February | 23°F | 60% | 47% | 8.7 mph | 47% | 38% |
| March | 31°F | 57% | 41% | 8.6 mph | 51% | 35% |
| April | 42°F | 59% | 43% | 7.7 mph | 55% | 28% |
| May | 54°F | 66% | 49% | 6.8 mph | 54% | 25% |
| June | 62°F | 67% | 49% | 6.1 mph | 63% | 14% |
| July | 63°F | 70% | 50% | 5.5 mph | 61% | 17% |
| August | 60°F | 71% | 51% | 5.6 mph | 63% | 17% |
| September | 51°F | 73% | 53% | 6.1 mph | 58% | 26% |
| October | 38°F | 68% | 50% | 6.8 mph | 55% | 30% |
| November | 30°F | 69% | 55% | 7.2 mph | 49% | 35% |
| December | 22°F | 67% | 55% | 7.7 mph | 47% | 39% |
Source: NOAA NCEI 1991-2020 hourly normals, station USW00014737. Monthly averages of all hours; afternoon humidity at 3 p.m. local standard time; sky as the share of hours NOAA's observations rate clear or few clouds (a dash where NOAA publishes no sky value).
How sunny is Allentown?
Over a year 72% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Allentown, 3.9 kWh per square metre a day. July is the sunniest month (79%) and December the cloudiest (63%). Among the 459 U.S. places of 50,000 or more, that ranks tied 385th (with 30 others) in sunshine.
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 65% | 1.9 |
| February | 68% | 2.7 |
| March | 67% | 3.6 |
| April | 70% | 4.8 |
| May | 69% | 5.3 |
| June | 74% | 5.9 |
| July | 79% | 6.0 |
| August | 77% | 5.2 |
| September | 75% | 4.2 |
| October | 69% | 3.0 |
| November | 70% | 2.1 |
| December | 63% | 1.6 |
Source: NASA POWER solar climatology, 2001-2020 (CERES SYN1deg). Satellite-based, for the 1-degree cell (about 100 km across) around the station, so it describes the area rather than the airport.
How much heating and cooling does Allentown need?
A normal year in Allentown brings 5,293 heating degree days, 1% fewer than the median U.S. place (5,373), and 981 cooling degree days, 8% more than the median (908). Seven months need 300 or more heating degree days, a monthly mean of about 55°F or colder. For gardens and crops, NOAA counts 3,405 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,082 | 0 |
| February | 913 | 0 |
| March | 755 | 0 |
| April | 403 | 8 |
| May | 151 | 60 |
| June | 19 | 196 |
| July | 1 | 328 |
| August | 3 | 268 |
| September | 69 | 108 |
| October | 334 | 13 |
| November | 632 | 0 |
| December | 932 | 0 |
| Year (annual) | 5,293 | 981 |
Source: NOAA NCEI 1991-2020 monthly normals, station USW00014737. A degree day is one degree of a day's mean temperature below 65°F (heating) or above it (cooling); utilities use them to estimate energy use.
Has Allentown been warmer than normal lately?
2025 averaged 52.2°F, 0.9°F below the 1991-2020 normal of 53.1°F. 3 of the 5 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. | Snow |
|---|---|---|---|---|
| 2021 | 53.3°F | +0.2°F | 44.67 | 45.1 |
| 2022 | 52.2°F | −0.9°F | 46.47 | 20.9 |
| 2023 | 53.6°F | +0.5°F | 46.38 | 4.9 |
| 2024 | 54.1°F | +1.0°F | 42.06 | 30.0 |
| 2025 | 52.2°F | −0.9°F | 37.51 | 20.7 |
Over 90 complete years from 1925 to 2025, the station's annual mean temperature rose at a fitted 4.8°F per century (+0.27°C per decade). A fitted rate summarizes the whole record; single years swing well above and below it.
Source: observed years: ACIS, station USW00014737; trend: NOAA GHCN-Monthly v4. A year counts only with all twelve months complete.
How does Allentown's climate compare?
Allentown is warmer than 95 of the other 107 places with their own NOAA record in Pennsylvania, and wetter than 82. Across the 7,247 U.S. stations with normals, its annual mean of 53.1°F is warmer than 54%.
In the Köppen classification computed from these normals, Allentown is Dfa: continental, no dry season, hot summer. What the classes mean.
Places with the most similar year elsewhere
Measured month by month on the normal high, low and precipitation, among places of 20,000 or more people in other states:
Source: NOAA NCEI 1991-2020 normals for every station PlainClimate covers. Similarity: the root-mean-square difference of the 36 monthly figures, precipitation weighted so an inch counts like 6°F.
Which places near Allentown share this climate record?
16 places have no NOAA station with 1991-2020 normals of their own, and this station is the nearest full record. A place's own climate can differ from these figures, by several degrees where it sits much higher or lower than the station, nearer the coast, or inside a large city's heat; for the larger places the next nearest records are named with their yearly mean, so the spread around them is visible, and places of 50,000 or more have their own page with NOAA's gridded normals.
- Fullerton, PA16,729 people · 2 mi SW
- Emmaus, PA12,314 people · 8 mi S
- Northampton, PA10,587 people · 3 mi NW
- Wescosville, PA7,156 people · 8 mi SW
- Catasauqua, PA6,625 people · 1 mi W
- Dorneyville, PA5,082 people · 6 mi SW
- Schnecksville, PA3,948 people · 9 mi W
- Coplay, PA3,555 people · 3 mi NW
- North Catasauqua, PA3,126 people · 2 mi NW
- Hokendauqua, PA3,037 people · 2 mi W
- Egypt, PA2,964 people · 5 mi NW
- Cetronia, PA2,338 people · 7 mi SW
- Cherryville, PA1,541 people · 9 mi NW
- Cementon, PA1,399 people · 4 mi NW
- Stiles, PA1,353 people · 3 mi W
- Laurys Station, PA547 people · 7 mi NW
Source: Census Bureau 2024 Gazetteer (place centers) and Vintage 2024 population estimates. Distance and direction from the station to each place's center.
Questions about Allentown's climate
What is the coldest month in Allentown?
January, with a normal high of 38°F and a normal low of 22°F. The warmest is July (86°F by day, 65°F at night).
Does it snow in Allentown?
Yes: 33 inches in a normal year, falling on 16 days with 0.1 inch or more, the most in February (10.8 inches).
What is the rainiest month in Allentown?
July, with 5.30 in of precipitation in a normal year; the driest is February with 2.77 in.
What plant hardiness zone is Allentown in?
The USDA's 2023 map puts Allentown in zone 7a across its 4 ZIP code areas (7a in 18103, the largest). By the same method at Allentown's NOAA station, the coldest night of a typical year reaches 2°F (30 years, 1991-2020): zone 7a.
How late can frost come in Allentown?
In half of years the last 32°F night comes after April 20; in one year in ten it comes after May 6. Waiting until May 6 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Allentown in OctoberThis month day by day, its records and recent years
- Pennsylvania climateThe statewide normals and every place in the state
- Springtown (1 mi NNE), PA11 miles from this station, 50.9°F a year
- Phillipsburg, NJ14 miles from this station, 52.1°F a year
- Rodale Research Center, PA16 miles from this station, 51.5°F a year
- Bucksville, PA17 miles from this station, 51.6°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made