The Louisville year in pollen
Pollen seasons in Louisville: tree pollen January to May, grass April to September, and ragweed from early August until the first frost, around November 7.
First frost lands around November 7 in Louisville — about 7 days later than Kentucky overall — which shifts when ragweed season ends here.
When does ragweed season end in Louisville?
Ragweed season in Louisville typically ends with the first frost, around November 7. Some years it comes as early as November 2, some as late as November 12.
A light frost around November 7 knocks the season down; the hard freeze that finishes it usually follows by November 17. Based on 30 years of NOAA frost records (1991–2020).
The rest of the Louisville pollen year
| Allergen | Typical season |
|---|---|
| Oak | March to May |
| Pine | March to May |
| Eastern red cedar | January to March |
| Maple | February to April |
| Birch | March to April |
| Hickory | April to May |
| Grass | April to September |
Season-by-season detail is on the Kentucky page.
Nearby calendars
Frost dates for Louisville come from the Louisville International Airport weather station's 30-year records. Season windows reviewed August 2026.