The Medford year in pollen
Pollen seasons in Medford: tree pollen January to June, grass March to July, and ragweed from early August until the first frost, around October 29.
Medford's pollen year runs on a different clock than most of Oregon — the seasons below follow Medford's own climate, not the statewide picture.
When does ragweed season end in Medford?
Ragweed season in Medford typically ends with the first frost, around October 29. Some years it comes as early as October 23, some as late as November 4.
A light frost around October 29 knocks the season down; the hard freeze that finishes it usually follows by November 13. Based on 30 years of NOAA frost records (1991–2020).
The rest of the Medford pollen year
| Allergen | Typical season |
|---|---|
| Oak | March to May |
| Cypress and juniper | January to March |
| Alder | January to March |
| Olive | April to June |
| Walnut | April to May |
| Grass | March to July |
Season-by-season detail is on the Oregon page.
Nearby calendars
Frost dates for Medford come from the Medford Rogue Vly Airport weather station's 30-year records. Season windows reviewed August 2026.