The Eugene year in pollen
Pollen seasons in Eugene: tree pollen February to May, grass May to July, and ragweed from mid-August until the first frost, around October 23.
Tree pollen
Grass
Ragweed
When does ragweed season end in Eugene?
Ragweed season in Eugene typically ends with the first frost, around October 23. Some years it comes as early as October 15, some as late as October 31.
A light frost around October 23 knocks the season down; the hard freeze that finishes it usually follows by November 11. Based on 30 years of NOAA frost records (1991–2020).
The rest of the Eugene pollen year
| Allergen | Typical season |
|---|---|
| Alder | February to April |
| Birch | March to May |
| Cottonwood | March to May |
| Oak | April to May |
| Grass | May to July |
Season-by-season detail is on the Oregon page.
Nearby calendars
Frost dates for Eugene come from the Eugene Mahlon Sweet Airport weather station's 30-year records. Season windows reviewed August 2026.