The Dover year in pollen
Pollen seasons in Dover: tree pollen March to June, grass May to July, and ragweed from early August until the first frost, around October 23.
Tree pollen
Grass
Ragweed
When does ragweed season end in Dover?
Ragweed season in Dover typically ends with the first frost, around October 23. Some years it comes as early as October 17, some as late as October 29.
A light frost around October 23 knocks the season down; the hard freeze that finishes it usually follows by November 2. Based on 30 years of NOAA frost records (1991–2020).
The rest of the Dover pollen year
| Allergen | Typical season |
|---|---|
| Oak | March to May |
| Maple | March to April |
| Birch | March to May |
| Ash | March to April |
| Pine | April to June |
| Grass | May to July |
Season-by-season detail is on the Delaware page.
Nearby calendars
Frost dates for Dover come from the Millville Municipal Airport weather station's 30-year records. Season windows reviewed August 2026.