How long is the allergy season?

Weeks to months: It depends on the pollen you are sensitized to and your location. In southern california, the mild weather allows much longer pollenating seasons than in the northeast. The exact season depends on which pollen, with grasses generally in the late spring, trees in late winter and early spring, and weeds in summer and early fall. Weather and local conditions can make this vary, though.

Depends on location: In the southern us, the allergy seasons are longer than in the northern us. In montana, trees typically pollinate for 2 months in the spring, grass for a couple of months in the early summer, weeds for a few months in late summer-fall; and mold from mid-summer into fall. "year-round" allergies are due primarily to indoor allergens such as dust mite, animal dander, cockroach and indoor mold.