The Caribou year in pollen
Pollen seasons in Caribou: tree pollen March to June, grass May to July, and ragweed from mid-August until the first frost, around October 1.
Tree pollen
Grass
Ragweed
When does ragweed season end in Caribou?
Ragweed season in Caribou typically ends with the first frost, around October 1. Some years it comes as early as September 25, some as late as October 5.
A light frost around October 1 knocks the season down; the hard freeze that finishes it usually follows by October 12. Based on 30 years of NOAA frost records (1991–2020).
The rest of the Caribou pollen year
| Allergen | Typical season |
|---|---|
| Maple | March to April |
| Birch | April to May |
| Oak | April to June |
| Ash | April to May |
| Pine | May to June |
| Grass | May to July |
Season-by-season detail is on the Maine page.
Nearby calendars
Frost dates for Caribou come from the Caribou Municipal Airport weather station's 30-year records. Season windows reviewed August 2026.