The Bend year in pollen
Pollen seasons in Bend: tree pollen March to June, grass May to July, and ragweed from early August until the first frost, around September 14.
Bend's pollen year runs on a different clock than most of Oregon — the seasons below follow Bend's own climate, not the statewide picture.
When does ragweed season end in Bend?
Ragweed season in Bend typically ends with the first frost, around September 14. Some years it comes as early as September 8, some as late as September 22.
A light frost around September 14 knocks the season down; the hard freeze that finishes it usually follows by September 30. Based on 30 years of NOAA frost records (1991–2020).
The rest of the Bend pollen year
| Allergen | Typical season |
|---|---|
| Juniper | March to May |
| Cottonwood and aspen | March to May |
| Maple (boxelder) | March to May |
| Birch and alder | April to May |
| Pine | May to June |
| Grass | May to July |
Season-by-season detail is on the Oregon page.
Nearby calendars
Frost dates for Bend come from the Redmond Roberts Field weather station's 30-year records. Season windows reviewed August 2026.