Baltimore, MD Pollen Levels Today

Baltimore's location along the Chesapeake Bay, combined with its humid subtropical climate and mix of urban and wooded landscapes, creates a prolonged and intense allergy season that often stretches from late February through October.

Tree pollen typically kicks off the year in early to mid-March and peaks in April, with oak, maple, birch, cedar, sycamore, and river birch being the dominant local offenders—oak in particular blankets the region with heavy yellow pollen loads.

As tree season winds down in May, grass pollen takes over, peaking from late May through early July. Timothy, orchard, Kentucky bluegrass, and Bermuda grass are the primary drivers, and their overlap with lingering tree pollen often intensifies symptoms in late spring.

Weed season follows in August and runs through the first frost, usually in late October, with ragweed as the leading culprit alongside lamb's quarters, pigweed, and plantain.

Baltimore's humidity also fuels year-round mold spores, especially outdoor molds like alternaria and cladosporium during warm months and indoor molds in older row homes. Urban air pollution, ozone, and dust mites further aggravate symptoms.

Overall, Baltimore's allergy profile is defined by a long, overlapping pollen calendar amplified by humidity, mold, and city air quality.