The New Haven year in pollen
Pollen seasons in New Haven: tree pollen March to June, grass May to July, and ragweed from mid-August until the first frost, around October 27.
Tree pollen
Grass
Ragweed
When does ragweed season end in New Haven?
Ragweed season in New Haven typically ends with the first frost, around October 27. Some years it comes as early as October 20, some as late as November 1.
A light frost around October 27 knocks the season down; the hard freeze that finishes it usually follows by November 6. Based on 30 years of NOAA frost records (1991–2020).
The rest of the New Haven 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 Connecticut page.
Nearby calendars
Frost dates for New Haven come from the New Haven Tweed Airport weather station's 30-year records. Season windows reviewed August 2026.