The Rapid City year in pollen
Pollen seasons in Rapid City: tree pollen February to May, grass May to August, and ragweed from early August until the first frost, around October 1.
Tree pollen
Grass
Ragweed
When does ragweed season end in Rapid City?
Ragweed season in Rapid City typically ends with the first frost, around October 1. Some years it comes as early as September 25, some as late as October 5.
A light frost around October 1 knocks the season down; the hard freeze that finishes it usually follows by October 9. Based on 30 years of NOAA frost records (1991–2020).
The rest of the Rapid City pollen year
| Allergen | Typical season |
|---|---|
| Eastern red cedar | February to April |
| Elm | February to April |
| Maple | March to April |
| Oak | April to May |
| Cottonwood | April to May |
| Grass | May to August |
Season-by-season detail is on the South Dakota page.
Nearby calendars
Frost dates for Rapid City come from the Rapid City Regional Airport weather station's 30-year records. Season windows reviewed August 2026.