The Olympia year in pollen
Pollen seasons in Olympia: tree pollen February to May, grass May to July, and ragweed from mid-August until the first frost, around October 14.
Tree pollen
Grass
Ragweed
When does ragweed season end in Olympia?
Ragweed season in Olympia typically ends with the first frost, around October 14. Some years it comes as early as October 6, some as late as October 21.
A light frost around October 14 knocks the season down; the hard freeze that finishes it usually follows by November 1. Based on 30 years of NOAA frost records (1991–2020).
The rest of the Olympia 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 Washington page.
Nearby calendars
Frost dates for Olympia come from the Olympia Airport weather station's 30-year records. Season windows reviewed August 2026.