The Pittsburgh year in pollen
Pollen seasons in Pittsburgh: tree pollen March to June, grass May to July, and ragweed from mid-August until the first frost, around October 28.
Tree pollen
Grass
Ragweed
When does ragweed season end in Pittsburgh?
Ragweed season in Pittsburgh typically ends with the first frost, around October 28. Some years it comes as early as October 22, some as late as November 2.
A light frost around October 28 knocks the season down; the hard freeze that finishes it usually follows by November 8. Based on 30 years of NOAA frost records (1991–2020).
The rest of the Pittsburgh 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 Pittsburgh come from the Pittsburgh Allegheny Co Airport weather station's 30-year records. Season windows reviewed August 2026.