The Lancaster year in pollen
Pollen seasons in Lancaster: tree pollen March to June, grass May to July, and ragweed from mid-August until the first frost, around October 25.
Tree pollen
Grass
Ragweed
When does ragweed season end in Lancaster?
Ragweed season in Lancaster typically ends with the first frost, around October 25. Some years it comes as early as October 19, some as late as October 30.
A light frost around October 25 knocks the season down; the hard freeze that finishes it usually follows by November 5. Based on 30 years of NOAA frost records (1991–2020).
The rest of the Lancaster 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 Lancaster come from the Lancaster Airport weather station's 30-year records. Season windows reviewed August 2026.