Allergy season generally ends by late autumn when plants stop producing pollen and enter dormancy, which is typically around October or November depending on the region. For example, ragweed pollen, often signaling the end of the allergy season, usually ends after the first hard frost that happens in late October or early November in many areas. Grass pollen tends to subside by mid to late summer (July or August), and tree pollen often ends by late spring or early summer (May to June) depending on the location. In regions with milder climates, some allergens can persist longer, extending the allergy season.
In summary, most outdoor allergy seasons conclude by late fall, around October to November, marking the end of the primary pollen-related allergy symptoms for the year.
