Weather in Allentown, Pennsylvania
Roses open along the stoops. Day 59 of spring. Read this microseason across nine climate regions →
- TodayMay 16Overcast—82°44°
- SundayMay 17Overcast11%89°61°
- MondayMay 18Light Showers10%95°66°
- TuesdayMay 19Light Drizzle—89°66°
- WednesdayMay 20Light Showers75%86°58°
- ThursdayMay 21Overcast14%71°50°
- FridayMay 22Drizzle28%58°47°
- PM 2.5
- 9.6 μg/m³
- PM 10
- 9.9 μg/m³
- NO₂
- 7.1 μg/m³
- Ozone
- 108.0 μg/m³
- UV Index
- 0.0 Low
When the dew is on the grass, rain will never come to pass.
- Moonrise
- 9:47 AM
- Moonset
- 12:40 AM
- In sign
- ♊︎ Gemini
Roses open along the stoops
Allentown at a glance
- Today vs. normal: 69°F — typical for the season
- Last frost: April 20 (climatological average for this latitude)
- Microseason: 28 of 72, May 16–20
- Planting window: Direct sow okra, melons, and southern peas. Thin carrot rows.
Right now in the garden
Warm-season window is open
As of May 17, the last spring frost has passed for most years. Transplant tomatoes, peppers, eggplants, basil, and cucurbits (cucumbers, squash, melons) now. Direct-sow beans and corn into warm soil.
Planting calendar
| Month | Plant | Harvest |
|---|---|---|
| January | — | — |
| February | — | — |
| March | — | — |
| April | lettuce, peas, spinach, radishes | — |
| May | lettuce, peas, spinach, radishes, tomatoes, peppers, beans, squash | lettuce, peas, radishes |
| June | tomatoes, peppers, beans, squash | lettuce, peas, radishes |
| July | tomatoes, peppers, beans, squash | tomatoes, beans, summer squash |
| August | — | tomatoes, beans, summer squash |
| September | fall brassicas, garlic (overwinter), carrots | tomatoes, beans, summer squash |
| October | fall brassicas, garlic (overwinter), carrots | winter squash, tomatoes (last) |
| November | — | — |
| December | — | — |
A year in weather
July brings Allentown's warmest temperatures (~76°F mean) while January delivers the coldest (~30°F). Rainfall reaches its peak in July (5.3 inches) and drops to its lowest point in February (2.8 inches).
| Month | Mean temp | Precip | Rainy days |
|---|---|---|---|
| January | 30° | 3.3″ | 6 |
| February | 32° | 2.8″ | 6 |
| March | 41° | 3.6″ | 7 |
| April | 52° | 3.7″ | 7 |
| May | 62° | 3.6″ | 8 |
| June | 71° | 4.4″ | 7 |
| July | 76° | 5.3″ | 8 |
| August | 74° | 4.6″ | 7 |
| September | 66° | 4.8″ | 7 |
| October | 55° | 4.1″ | 6 |
| November | 44° | 3.2″ | 6 |
| December | 35° | 3.9″ | 7 |
Regional context
Allentown belongs to a warm-summer humid continental climate region — sharing similar temperature ranges, seasonal patterns, and growing conditions with nearby cities.
Similar climates: Philadelphia, PA, Pittsburgh, PA, Harrisburg, PA, Lancaster, PA, Scranton, PA.
Naturalist notes
During late May, red-winged blackbirds establish territories in the wetlands around Allentown's waterways.
Apple trees throughout the region typically finish blooming by early May as temperatures stabilize.
Frequently asked
- When does it freeze in Allentown?
- Around mid-April, Allentown typically sees its last spring frost, with the first fall frost returning around mid-November.
- What is the rainy season in Allentown?
- About 5.3 inches of rain fall during July, the wettest month; the city receives roughly 47 inches annually.
- What is the warmest month in Allentown?
- July typically brings the warmest weather, averaging about 76°F.
- What is the coldest month in Allentown?
- January typically brings the coldest weather, averaging about 30°F.
- When can I start a vegetable garden in Allentown?
- Around the last spring frost (mid-April), cool-season crops (peas, lettuce) can be sown; warm-season crops (tomatoes, peppers) should wait until 1–2 weeks after.
- How many rainy days does Allentown get?
- About 82 rainy days occur in Allentown per year.
- What hardiness zone is Allentown?
- Check the USDA's online lookup with the city ZIP for Allentown's current hardiness zone designation, which is determined by its lowest average winter temperature.
Climate
Allentown, Pennsylvania sits in a warm-summer humid continental climate zone. January temperatures hover near 30°F while July averages 76°F — a 45°F seasonal swing.
Throughout the year, Allentown receives about 47 inches of precipitation spread over roughly 82 rainy days.
Latitude (40.6°N), proximity to large water bodies, and elevation set the rhythm of the year — shaping what grows here, when frost is likely, and what the weather story looks like day to day.