Washington, DC Pollen Levels Today

Washington, DC sits in a humid subtropical climate zone where a long growing season, mild winters, and abundant green space combine to produce one of the more challenging allergy environments on the East Coast.

The allergy calendar typically opens in late February or early March with tree pollen, which dominates through May and tends to be the most intense season for local sufferers. Oak, maple, birch, cedar, elm, sycamore, and the notoriously potent river birch and mulberry are widespread across the District's tree-lined streets and nearby parklands, with oak often driving peak counts in April.

As tree pollen tapers, grass pollen ramps up from mid-May through July, led by timothy, orchard, Bermuda, and Kentucky bluegrass. Late spring frequently brings an overlap of lingering tree and emerging grass pollen, a period when symptoms often intensify sharply.

By mid-August, weed pollen takes over and runs through the first hard frost in October or November, with ragweed as the dominant trigger alongside pigweed, plantain, and lamb's quarters.

The region's humidity also fuels year-round mold spores, while urban air pollution, dust, and pollen trapped along the Potomac basin can worsen reactions.

Overall, DC's profile is defined by a long, overlapping, and pollen-heavy season.