As the weather warms up across the United States this spring, pollen and seasonal allergies ramp up as well. AccuWeather has released its latest allergy forecast for 2025, and meteorologists warn that it could be a particularly bad year for many regions. The allergy season is expected to last throughout the summer, affecting millions of people from the mid-Atlantic to the Pacific Northwest. Unfortunately, seasonal allergies have become increasingly common for both adults and children, raising concerns for the upcoming season.

Common allergies across the U.S. include pollen from trees, grass, and ragweed, each peaking at different times throughout the spring and summer months. Ahead, we share when to expect the worst allergies of 2025, according to the experts at AccuWeather.

Tree Pollen

Tree pollen is the first allergen to sweep across the southern region of the country as temperatures warm up there first. Once temperatures rise to 40-45 degrees Fahrenheit, trees begin to grow and produce pollen. The Gulf Coast, central Plains, northern Rockies, and Pacific Northwest will experience the worst tree pollen this year. “Drier weather in the Southwest through the spring will help to end the season after a rapid start,” says Alan Reppert, AccuWeather senior meteorologist and allergy expert.

Grass Pollen

Once the tree pollen wanes, the grass pollen begins come April as grass starts to grow along the Gulf Coast. According to Reppert, grass pollen can last throughout the summer and even into early fall. Dry weather in the summer helps limit the grass pollen in states such as Florida, Georgia, Alabama, and South Carolina. In the Northeast and Pacific Northwest, grass allergens will be the worst in June and July due to the warm and wet summer climate.

Ragweed Pollen

Ragweed pollen usually begins during the grass pollen season and thrives on the moisture that arrives late in the summer. The Tennessee Valley is predicted to experience a dual peak this year, making it the worst region for people who struggle with ragweed allergies.

Regions such as the coastal Carolinas, southern Plains, and parts of the Gulf Coast may also see a growth in ragweed allergens due to their more tropical, moist climate. Lower ragweed pollen levels are predicted for the Northwest, Rockies, and northern Plains this year, offering relief after months of intense tree and grass pollen.