Allergies are a result of an overreaction in some individuals to allergens or substances that generally do not affect others. Some allergies are year-round, such as those to animal dander, dust mites, foods, medicines, and mold. Other allergies are seasonal and affect individuals during only certain times of the year. These seasonal allergies fall under the broad name of hay fever, aptly named after hay-cutting season. Hay fever is typically the result of pollen produced by plants such as grass, trees, and weeds
These allergies occur between spring and fall, depending on the weather and the geographic location. Many who suffer from seasonal allergies have an overlap of allergies and experience symptoms throughout the season. Spring allergies often begin in February with tree pollination, followed by grass pollination in the spring and summer and, finally, weed pollination, especially of ragweed, in the late summer to early fall.