Illinois Pollen by City

Most of Illinois's cities read the warm, humid subtropical Southeast pollen calendar: tree pollen peaks Feb–Apr, grass Apr–Sep, and ragweed Aug–Nov — an unusually long, overlapping season — the warm climate stretches grass across much of the year and pushes ragweed deep into autumn. Every city below has its own page with today’s verdict and the full 12-month season calendar.

Cities in Illinois

5 cities with a pollen page, largest first

CityTree pollen seasonPopulation
ChicagoMar–May8,609,571
RockfordMar–May271,411
Round Lake BeachMar–May264,501
PeoriaMar–May255,063
WoodstockMar–May26,147

Our dataset lists 1,456 places in Illinois; the 5 above have a page. For a smaller town, the nearest city above is the closest match.