The Allentown year in pollen
Pollen seasons in Allentown: tree pollen March to June, grass May to July, and ragweed from mid-August until the first frost, around October 24.
First frost lands around October 24 in Allentown — about 4 days earlier than Pennsylvania overall — which shifts when ragweed season ends here.
When does ragweed season end in Allentown?
Ragweed season in Allentown typically ends with the first frost, around October 24. Some years it comes as early as October 17, some as late as October 31.
A light frost around October 24 knocks the season down; the hard freeze that finishes it usually follows by November 4. Based on 30 years of NOAA frost records (1991–2020).
The rest of the Allentown pollen year
| Allergen | Typical season |
|---|---|
| Maple | March to April |
| Birch | April to May |
| Oak | April to June |
| Ash | April to May |
| Pine | May to June |
| Grass | May to July |
Season-by-season detail is on the Pennsylvania page.
Nearby calendars
Frost dates for Allentown come from the Allentown International Airport weather station's 30-year records. Season windows reviewed August 2026.