The Maryland year in pollen

When does ragweed season end in Maryland?

Ragweed season in Maryland typically ends with the first frost, around November 4. The coldest corners of the state see frost by late October; the mildest hold out until late 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 Maryland

Tree pollen in Maryland starts in early March, and maple is usually first out. Oak — the bigger problem for most people — follows March to May. Mild springs pull the start earlier.

Grass season

Grass pollen in Maryland runs May to July, heaviest mid-May to mid-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 Maryland 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 Maryland?

Ragweed season in Maryland typically ends with the first frost, around November 4. The coldest corners of the state see frost by late October; the mildest hold out until late November.

When does allergy season end in Maryland?

The last big wave of the Maryland pollen year is ragweed, so the season ends with the first frost, around November 4. Tree pollen is done by June, grass mostly by July.

When does tree pollen start in Maryland?

Tree pollen in Maryland starts in early March, and maple is usually first out. Oak — the bigger problem for most people — follows March to May. Mild springs pull the start earlier.