The Sheridan year in pollen
Pollen seasons in Sheridan: tree pollen March to June, grass May to July, and ragweed from early August until the first frost, around September 23.
Tree pollen
Grass
Ragweed
When does ragweed season end in Sheridan?
Ragweed season in Sheridan typically ends with the first frost, around September 23. Some years it comes as early as September 18, some as late as September 28.
A light frost around September 23 knocks the season down; the hard freeze that finishes it usually follows by October 3. Based on 30 years of NOAA frost records (1991–2020).
The rest of the Sheridan pollen year
| Allergen | Typical season |
|---|---|
| Juniper | March to May |
| Cottonwood and aspen | March to May |
| Maple (boxelder) | March to May |
| Birch and alder | April to May |
| Pine | May to June |
| Grass | May to July |
Season-by-season detail is on the Wyoming page.
Nearby calendars
Frost dates for Sheridan come from the Sheridan Co Airport weather station's 30-year records. Season windows reviewed August 2026.