The St. Cloud year in pollen
Pollen seasons in St. Cloud: tree pollen March to June, grass May to July, and ragweed from mid-August until the first frost, around September 30.
Tree pollen
Grass
Ragweed
When does ragweed season end in St. Cloud?
Ragweed season in St. Cloud typically ends with the first frost, around September 30. Some years it comes as early as September 25, some as late as October 4.
A light frost around September 30 knocks the season down; the hard freeze that finishes it usually follows by October 8. Based on 30 years of NOAA frost records (1991–2020).
The rest of the St. Cloud pollen year
| Allergen | Typical season |
|---|---|
| Birch | April to May |
| Oak | April to June |
| Maple | March to May |
| Alder | March to April |
| Ash | April to May |
| Pine | May to June |
| Grass | May to July |
Season-by-season detail is on the Minnesota page.
Nearby calendars
Frost dates for St. Cloud come from the St Cloud Regional Airport weather station's 30-year records. Season windows reviewed August 2026.