Ragweed can start pollinating as early as July in some states, but for most of the country, ragweed season starts in August and peaks in mid-September, according to the Asthma and Allergy Foundation of America (AAFA). In some cases, it can last until November.

Ragweed starts pollinating as early as July in some states, especially states in the South. But for most of the country, it appears in August and peaks in mid-September. Ragweed pollen can stick around as late as October, depending on where you live.