The Grand Junction year in pollen
Pollen seasons in Grand Junction: tree pollen March to June, grass May to July, and ragweed from early August until the first frost, around October 16.
First frost lands around October 16 in Grand Junction — about 8 days later than Colorado overall — which shifts when ragweed season ends here.
When does ragweed season end in Grand Junction?
Ragweed season in Grand Junction typically ends with the first frost, around October 16. Some years it comes as early as October 10, some as late as October 22.
A light frost around October 16 knocks the season down; the hard freeze that finishes it usually follows by October 27. Based on 30 years of NOAA frost records (1991–2020).
The rest of the Grand Junction 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 Colorado page.
Nearby calendars
Frost dates for Grand Junction come from the Grand Junction Walker Field weather station's 30-year records. Season windows reviewed August 2026.