Pollen Count & Forecast for Washington, D.C.

Washington’s spring allergy season (March-May) is dominated by Oak and Birch pollen; Oak (Quercus) prolific in Rock Creek Park and the National Arboretum; Birch (Betula) widespread across city streets and squares. Maple (Acer) contributes significantly from the National Mall. Summer (June-August) sees high Grass (Poaceae) pollen levels, originating from the Potomac and Anacostia riverbanks.

The city’s low-lying basin and high humidity trap pollen, leading to localised high concentrations. Autumn and winter see elevated Mould (Alternaria, Cladosporium) spore counts, from decomposing leaf litter along the Capital Crescent Trail and damp river corridors. Indoor mould persists in older residential buildings.