Home Accuweather.com U.S. Fall Allergy Surge: Weed Pollen Rises as Grass Counts Linger (Video)

U.S. Fall Allergy Surge: Weed Pollen Rises as Grass Counts Linger (Video)

Aug 21, 2026

Fall allergy season is ramping up across the United States, with warm and wet weather helping pollen levels climb in parts of the country.

Grass and weed pollen are the biggest concerns during the end of summer and start of fall. AccuWeather’s 2026 U.S. Fall Allergy Forecast shows grass pollen gradually declining during August and early September, while weed pollen is expected to become more widespread into October.

“For grass pollen, we start to lose the worst of it in August and early September, but things can still be high in parts of the East due to ample moisture and warm overnight temperatures,” AccuWeather Senior Meteorologist Alan Reppert said.

The highest grass pollen levels are forecast across parts of the Midwest, Great Lakes, Northeast, and mid-Atlantic, including Chicago, Detroit, New York City and Philadelphia. Increasing dryness across much of the West is expected to slow grass growth outside of irrigated areas, while much of the Southeast should have some dry stretches which will keep grass pollen below the historical average.

Weed Pollen Becomes the Bigger Concern This Fall

Southeast and southern Rockies: Rainfall associated with El Niño, combined with persistent warmth, is expected to promote weed growth and extend the pollen season
Highest pollen levels: Raleigh, Nashville, Atlanta, Little Rock, Denver, Salt Lake City and Albuquerque are among the cities forecast to experience high weed pollen levels
Northern U.S.: Drier conditions are expected to restrict weed growth, keeping the overall season below the historical average
Rain can bring short-term swings: Rain can temporarily reduce airborne pollen, but subsequent weed growth can contribute to higher pollen levels during the days that follow

For a personalized view of how pollen and other health factors may affect people today, check the Live a Healthier Life™ section in the AccuWeather app, which delivers daily allergy insights tailored to a specific users’ location.

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