The Sioux Falls year in pollen
Pollen seasons in Sioux Falls: tree pollen February to May, grass May to August, and ragweed from early August until the first frost, around October 6.
First frost lands around October 6 in Sioux Falls — about 5 days later than South Dakota overall — which shifts when ragweed season ends here.
When does ragweed season end in Sioux Falls?
Ragweed season in Sioux Falls typically ends with the first frost, around October 6. Some years it comes as early as September 30, 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 Sioux Falls 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 Sioux Falls come from the Sioux Falls weather station's 30-year records. Season windows reviewed August 2026.