The Rockford year in pollen
Pollen seasons in Rockford: tree pollen February to May, grass May to July, and ragweed from early August until the first frost, around October 17.
Tree pollen
Grass
Ragweed
When does ragweed season end in Rockford?
Ragweed season in Rockford typically ends with the first frost, around October 17. Some years it comes as early as October 12, some as late as October 22.
A light frost around October 17 knocks the season down; the hard freeze that finishes it usually follows by October 28. Based on 30 years of NOAA frost records (1991–2020).
The rest of the Rockford pollen year
| Allergen | Typical season |
|---|---|
| Oak | April to May |
| Maple | March to April |
| Elm | February to April |
| Birch | April to May |
| Ash | April to May |
| Hickory and walnut | April to May |
| Grass | May to July |
Season-by-season detail is on the Illinois page.
Nearby calendars
Frost dates for Rockford come from the Rockford Gtr Rockford Airport weather station's 30-year records. Season windows reviewed August 2026.