The St. George year in pollen
Pollen seasons in St. George: tree pollen March to June, grass May to July, and ragweed from early August until the first frost, around September 29.
First frost lands around September 29 in St. George — about 23 days earlier than Utah overall — which shifts when ragweed season ends here.
When does ragweed season end in St. George?
Ragweed season in St. George typically ends with the first frost, around September 29. Some years it comes as early as September 25, some as late as October 5.
A light frost around September 29 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 St. George 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 Utah page.
Nearby calendars
Frost dates for St. George come from the Cedar City Municipal Airport weather station's 30-year records. Season windows reviewed August 2026.