Usually called "hay fever," seasonal allergic rhinitis is caused by an allergy to the pollen of trees, grasses, weeds or mold spores. Seasonal allergic rhinitis may occur in the spring, summer or fall and may last until the first frost. The "season" depends on which allergen causes the reaction, the region of the country and pollination periods. Symptoms include sneezing, itching and watery eyes, runny nose, burning palate and throat. These seasonal allergies have been known to trigger asthma.