Seasonal allergies are caused by exposure to airborne substances, such as pollens, that appear only during certain times of the year. The most common allergens are pollens from wind-pollenated plants, such as trees, grasses, and ragweed. Other triggers of seasonal allergies include mold spores, which can be airborne for long periods of time during the spring, summer, and fall. The timing and severity of an allergy season vary across the country, but tree, grass, and ragweed pollens thrive during cool nights and warm days, while molds grow quickly in heat and high humidity. The following are common seasonal allergy triggers:

• Tree pollen (especially from birches, oaks, elms, and maples) typically appears in spring.
• Grass pollen is shed in late spring and summer.
• Ragweed produces pollen in the fall.
• Mold spores often cause seasonal allergies during the spring, summer, and fall. They may also cause year-round allergies for people who live in buildings with too much moisture.

If you suspect you have seasonal allergies, its important to talk to your doctor. They can help diagnose the cause and recommend appropriate treatment.