The Connecticut year in pollen

When does ragweed season end in Connecticut?

Ragweed season in Connecticut typically ends with the first frost, around October 27. 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 Connecticut

Tree pollen in Connecticut starts in mid-March, and maple is usually first out. Oak — the bigger problem for most people — follows April to June. Mild springs pull the start earlier.

Grass season

Grass pollen in Connecticut runs May to July, heaviest early June to late June. The culprits are cool-season lawn and meadow grasses — timothy, bluegrass, orchard grass — which flower in one early-summer wave. More on grass seasons.

First frost — and ragweed's end — city by city

The first frost sweeps across Connecticut over several weeks, and ragweed season ends with it. Based on 30 years of NOAA frost records (1991–2020).

Common questions

When does ragweed season end in Connecticut?

Ragweed season in Connecticut typically ends with the first frost, around October 27. The coldest corners of the state see frost by late October; the mildest hold out until early November.

When does allergy season end in Connecticut?

The last big wave of the Connecticut pollen year is ragweed, so the season ends with the first frost, around October 27. Tree pollen is done by June, grass mostly by July.

When does tree pollen start in Connecticut?

Tree pollen in Connecticut starts in mid-March, and maple is usually first out. Oak — the bigger problem for most people — follows April to June. Mild springs pull the start earlier.