The Kentucky year in pollen
Tree pollen in Kentucky runs January to May, grass follows April to September, and ragweed starts in early August and holds on until the first frost — typically around October 31.
When does ragweed season end in Kentucky?
Ragweed season in Kentucky typically ends with the first frost, around October 31. The coldest corners of the state see frost by late October; the mildest hold out until early November.
Ragweed keeps releasing pollen until a freeze kills the plants, which is why the season has no fixed end date — it ends when the cold arrives. More on how frost ends ragweed season.
Tree pollen in Kentucky
Tree pollen in Kentucky starts in mid-January, and eastern red cedar is usually first out. Oak — the bigger problem for most people — follows March to May. Mild springs pull the start earlier.
| Tree | Typical season | Heaviest weeks |
|---|---|---|
| Oak | March to May | late March to late April |
| Pine | March to May | mid-March to mid-April |
| Eastern red cedar | January to March | early February to early March |
| Maple | February to April | — |
| Birch | March to April | — |
| Hickory | April to May | — |
Grass season
Grass pollen in Kentucky runs April to September, heaviest early May to late June. Cool-season grasses flower in the first wave; warm-season grasses like Bermuda pick up through summer, which stretches the season. More on grass seasons.
First frost — and ragweed's end — city by city
The first frost sweeps across Kentucky over several weeks, and ragweed season ends with it. Based on 30 years of NOAA frost records (1991–2020).
| City | Typical first frost |
|---|---|
| Bowling Green | October 31 |
| Lexington | October 28 |
| Louisville | November 7 |
Common questions
When does ragweed season end in Kentucky?
Ragweed season in Kentucky typically ends with the first frost, around October 31. The coldest corners of the state see frost by late October; the mildest hold out until early November.
When does allergy season end in Kentucky?
The last big wave of the Kentucky pollen year is ragweed, so the season ends with the first frost, around October 31. Tree pollen is done by May, grass mostly by September.
When does tree pollen start in Kentucky?
Tree pollen in Kentucky starts in mid-January, and eastern red cedar is usually first out. Oak — the bigger problem for most people — follows March to May. Mild springs pull the start earlier.
Sources: NOAA U.S. Climate Normals (1991–2020 frost records) · Asthma and Allergy Foundation of America — Ragweed Pollen. Season windows reviewed August 2026.