Indianapolis, IN Pollen Levels Today

Indianapolis sits in central Indiana's humid continental climate zone, where distinct seasons and abundant deciduous forests create a long, intense allergy calendar that typically runs from March through October.

Tree pollen kicks off the season in early spring, with oak, maple, birch, cedar, elm, ash, and sycamore releasing heavy pollen loads from mid-March through May, peaking in April. As tree pollen tapers, grass season ramps up in mid-to-late May and persists through July, dominated by Kentucky bluegrass, timothy, orchard grass, and Bermuda grass—all widely planted across the city's lawns, parks, and surrounding farmland.

Late May and early June often bring a challenging overlap of lingering tree pollen and rising grass counts, which can intensify symptoms for multi-sensitive sufferers.

Weed pollen takes over in August and runs through the first hard frost in October, with ragweed as the primary culprit, followed by lamb's quarters, pigweed, and plantain thriving in Indiana's agricultural landscape.

Beyond pollen, Indianapolis's humid summers fuel outdoor mold spores (especially alternaria and cladosporium), while year-round dust mites and occasional ozone and particulate pollution add to the burden.

Overall, the city's allergy profile is defined by a lengthy, overlapping pollen season amplified by Midwestern humidity and persistent mold pressure.