The Billings year in pollen
Pollen seasons in Billings: tree pollen March to June, grass May to July, and ragweed from early August until the first frost, around October 7.
First frost lands around October 7 in Billings — about 11 days later than Montana overall — which shifts when ragweed season ends here.
When does ragweed season end in Billings?
Ragweed season in Billings typically ends with the first frost, around October 7. Some years it comes as early as October 1, some as late as October 14.
A light frost around October 7 knocks the season down; the hard freeze that finishes it usually follows by October 16. Based on 30 years of NOAA frost records (1991–2020).
The rest of the Billings 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 Montana page.
Nearby calendars
Frost dates for Billings come from the Billings Logan International Airport weather station's 30-year records. Season windows reviewed August 2026.