Allentown, Pennsylvania Weather
Apples hang heavy on the branch. Day 93 of summer. Read this microseason across nine climate regions →
Allentown weather forecast — hour by hour, 7-day outlook, NOAA radar
Conditions updated 10:15 AM EDT · Open-Meteo
- TodaySep 21Light Drizzle later13%—68°61°—
- TuesdaySep 22Light Drizzle40%0.02″61°55°-7°
- WednesdaySep 23Overcast——66°48°+5°
- ThursdaySep 24Overcast——67°46°+1°
- FridaySep 25Clear39%—72°48°+5°
- SaturdaySep 26Clear31%—75°50°+3°
- SundaySep 27Clear18%—77°53°+2°
Air quality now AQI 24 · Good
AQI 24 (Good), driven by Ozone. AQI flat over the last 6 hours (within ±3 points).
OK No precautions needed for the general population; unusually sensitive individuals may consider limiting prolonged outdoor exertion during the projected peak around 7 PM.
Trends
Seven days of AQI and PM2.5.
Hourly air-quality data from the Copernicus Atmosphere Monitoring Service, charted across the past and next several days. Dashed lines mark the AQI breakpoints at 50 (Good → Moderate) and 100 (Moderate → Unhealthy for Sensitive Groups).
September dries up ditches or breaks down bridges.
- Moonrise
- 4:36 PM
- Moonset
- 1:18 AM
- In sign
- ♑︎ Capricorn
Apples hang heavy on the branch
Read this microseason across nine climate regions →
All 72 microseasons on the year wheel →
Allentown at a glance
- Today vs. normal: Today averages 65°F (high 68°F, low 61°F), about the 65°F normal for Sep 21
- Last frost: April 20 (1991–2020 median, NOAA station 7 km away)
- Microseason: Sep 21–25
- Planting calendar: September — plant garlic (overwinter); harvest tomatoes, peppers, beans, summer squash, winter squash
16-Day Forecast — Allentown
- Mon68°61°13%
- Tue61°55°40%
- Wed66°48°6%
- Thu67°46°4%
- Fri72°48°39%
- Sat75°50°31%
- Sun77°53°18%
- Mon77°57°10%
- Tue76°59°10%
- Wed77°59°16%
- Thu75°61°20%
- Fri73°56°15%
- Sat74°54°16%
- Sun74°58°23%
- Mon72°54°23%
- Tue59°47°16%
Forecast data from Open-Meteo (CC BY 4.0).
Live wind & temperature near Allentown
Interactive wind and temperature map centered on Allentown — it loads in your browser. Open the full weather map.
Right now in the garden
Fall planting + final harvests
As of September 21, the season's first frost (typically October 24) is approaching. Pick what frost-tender plants still carry before the next cold front. This city's planting calendar for September: plant garlic (overwinter); harvest tomatoes, peppers, beans, summer squash, and winter squash.
Sun & seasons in Allentown
Allentown sits in Lehigh County, where the year’s longest day runs 15h 5m of daylight and its shortest just 9h 16m — a swing of +5h 49m between the June and December solstices. Clocks spring forward on Sunday, March 8, 2026 and fall back on Sunday, November 1, 2026.
Philadelphia, the state’s largest city, lies about 44 miles to the SSE. The nearest town Allentown tracks is Trumbauersville, roughly 14 miles to the SSE.
Air quality in Allentown
Air quality in Allentown’s county has trended cleaner since 2020; its cleanest year on record was 2024 (median AQI 39). See the full air-quality history for Allentown.
Planting calendar
| Month | Plant | Harvest |
|---|---|---|
| March | lettuce, peas, spinach, radishes | — |
| April | lettuce, peas, spinach, radishes | radishes |
| May | tomatoes, peppers, beans, squash | lettuce, peas, spinach, radishes |
| June | tomatoes, peppers, beans, squash | lettuce, peas, spinach, radishes |
| July | tomatoes, peppers, beans, squash | lettuce, peas, beans, summer squash, garlic |
| August | beans, squash, fall brassicas, carrots | tomatoes, peppers, beans, summer squash, winter squash |
| September | garlic (overwinter) | tomatoes, peppers, beans, summer squash, winter squash |
| October | garlic (overwinter) | tomatoes, peppers, beans, summer squash, winter squash, fall brassicas, carrots |
| November | — | fall brassicas, carrots |
A year in weather
July is Allentown's warmest stretch (~75°F) and January its coldest (~29°F); precipitation crests in December at 4.3 inches and ebbs in February to 2.9 inches.
| Month | Mean temp | Precip |
|---|---|---|
| January | 29° | 3.4″ |
| February | 31° | 2.9″ |
| March | 40° | 3.7″ |
| April | 51° | 4.0″ |
| May | 60° | 4.1″ |
| June | 69° | 4.1″ |
| July | 75° | 3.4″ |
| August | 74° | 4.1″ |
| September | 67° | 3.9″ |
| October | 56° | 3.2″ |
| November | 43° | 3.8″ |
| December | 33° | 4.3″ |
Regional context
Similar climates Fullerton, PA, Dorneyville, PA, Cetronia, PA
In Allentown, modelled 1991-2020 normals (EC_Earth3P_HR model via Open-Meteo) put January near 29°F and July near 75°F — a 47°F seasonal arc — with about 44.9 inches of precipitation.
Rainfall in Allentown splits evenly between the seasons: December tops out at 4.3 inches, and February logs 2.9 inches — neither half of Allentown's year dominates. That lines Allentown up with places like Fullerton, PA, Dorneyville, PA and Cetronia, PA, fed by overlapping storm tracks.
Around April 20, Allentown sheds its freezing nights — kale, peas, spinach, and parsnips go into Allentown's beds. Tomatoes and peppers do best set out two weeks later in Allentown, once nights clear the mid-40s°F. The season ends by October 24 in Allentown, once hard frosts set back in. That date is a median: Allentown freezes sooner in half of years.
Similar climates: Fullerton, PA, Dorneyville, PA, Cetronia, PA, Catasauqua, PA, Fountain Hill, PA.
Frequently asked
- When does it freeze in Allentown?
- In Allentown, expect the last spring frost near April 20; Allentown's first autumn frost comes around October 24.
- What is the rainy season in Allentown?
- December is the wettest month in Allentown, about 4.3 inches on average; the year totals roughly 45 inches.
- What is the warmest month in Allentown?
- Allentown peaks in July, when the mean runs near 75°F.
- What is the coldest month in Allentown?
- January is Allentown's coldest month, averaging about 29°F.
- When can I start a vegetable garden in Allentown?
- In Allentown, sow peas and hardy greens around April 20; Allentown's tomatoes and peppers wait two weeks more.
- What hardiness zone is Allentown?
- Because Allentown bottoms near 29°F in January, that winter low sets Allentown's USDA zone — verify by ZIP.
- What is the 10-day forecast for Allentown?
- Allentown's extended outlook — daily high and low temperatures and precipitation chances for each upcoming day — is in the daily forecast above.
- Will it rain this week in Allentown?
- See this week's day-by-day rain chances for Allentown in the daily forecast above, and the next 24 hours in the hourly chart.
- What is the weather like right now in Allentown?
- Current conditions for Allentown and the next 24 hours — temperature, precipitation chance, and wind by the hour — are in the hourly forecast chart above.
- How often is the Allentown forecast updated?
- The Allentown forecast on this page is built from Open-Meteo weather-model data and refreshes regularly through the day.
- When are sunrise and sunset in Allentown?
- Today's sunrise and sunset times for Allentown are in the Almanac section above, along with civil dawn, civil dusk, and day length. Day length is longest near the summer solstice and shortest near the winter solstice.
- How accurate is the weather forecast for Allentown?
- The next few days in Allentown's forecast are the most reliable; accuracy declines beyond about a week as weather-model uncertainty grows.
Allentown sits at 40.6°N; its climate zone is warm-summer humid continental (Köppen approximation).
ZIP codes in Allentown
- 18001
- 18101
- 18102
- 18103
- 18104
- 18105
- 18106
- 18109
- 18195