One of the most common triggers for are spores. They are small, light and dry, so the wind can carry them. counts can vary day-to-day, depending on several factors, including the weather. For example, dry, windy weather spreads pollen quickly. However, heavy rains and humid weather conditions weigh down pollen, keeping it on the ground.2 In general, plants and trees that pollinate via wind cause the most problems for people with seasonal allergies.
Weed Pollen: Ragweed is a weed that grows in most parts of the United States. It is a potent and widespread cause of pollen symptoms. This tall, branched plant is found throughout the lower 48 states in dry fields, pastures and by roadsides.
Grass Pollen: There are hundreds of different grass types. However, only some cause allergies. The most common types of grasses that cause allergies include Bermuda, Johnson, Kentucky, Orchard, Rye, Sweet Vernal and Timothy. Grasses usually pollinate in the late spring and early summer in northern regions of the United States. In the south, grasses may pollinate across many seasons and could trigger allergy symptoms throughout the year.3
Tree Pollen: When it comes to trees, watch out for hardwood deciduous species, including birch, oak, elm, maple, ash, alder and hazel. These trees generally pollinate from late winter to the end of spring, depending on where you live.