The Rochester year in pollen
Pollen seasons in Rochester: tree pollen March to June, grass May to July, and ragweed from mid-August until the first frost, around October 6.
First frost lands around October 6 in Rochester — about 5 days later than Minnesota overall — which shifts when ragweed season ends here.
When does ragweed season end in Rochester?
Ragweed season in Rochester typically ends with the first frost, around October 6. Some years it comes as early as October 1, some as late as October 12.
A light frost around October 6 knocks the season down; the hard freeze that finishes it usually follows by October 17. Based on 30 years of NOAA frost records (1991–2020).
The rest of the Rochester 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 Rochester come from the Rochester International Airport weather station's 30-year records. Season windows reviewed August 2026.