The Cincinnati year in pollen
Pollen seasons in Cincinnati: tree pollen February to May, grass May to July, and ragweed from early August until the first frost, around October 25.
Tree pollen
Grass
Ragweed
When does ragweed season end in Cincinnati?
Ragweed season in Cincinnati typically ends with the first frost, around October 25. Some years it comes as early as October 20, 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 4. Based on 30 years of NOAA frost records (1991–2020).
The rest of the Cincinnati pollen year
| Allergen | Typical season |
|---|---|
| Oak | April to May |
| Maple | March to April |
| Elm | February to April |
| Birch | April to May |
| Ash | April to May |
| Hickory and walnut | April to May |
| Grass | May to July |
Season-by-season detail is on the Ohio page.
Nearby calendars
Frost dates for Cincinnati come from the Cincinnati Lunken Airport weather station's 30-year records. Season windows reviewed August 2026.