Fall allergy season is picking up across the United States as late-summer warmth and moisture drive up pollen counts in several regions, according to the latest AccuWeather 2026 U.S. Fall Allergy Forecast.
Grass and weed pollen remain the primary triggers for allergy sufferers during late summer and early autumn. Forecasters project that grass pollen will gradually taper off through August and early September, making way for widespread weed pollen to take over through 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,” said AccuWeather Senior Meteorologist Alan Reppert.
The highest concentrations of grass pollen are expected throughout the Midwest, Great Lakes, Northeast, and Mid-Atlantic, affecting major metropolitan areas such as Chicago, Detroit, New York City, and Philadelphia.
Meanwhile, drier weather across the West will likely limit grass growth outside of irrigated zones, and periodic dry spells across the Southeast are anticipated to keep grass pollen below historical averages.
As grass pollen eases, weed pollen is slated to become the more dominant concern. Rainfall tied to El Niño, paired with lingering warm temperatures, is projected to fuel weed growth and lengthen the allergy season across the Southeast and southern Rockies.
Cities likely to see elevated weed pollen counts include Atlanta, Nashville, Raleigh, Little Rock, Denver, Salt Lake City, and Albuquerque.
In contrast, drier conditions across the northern tier of the country are expected to curb weed growth, keeping the overall season below average in those areas. Meteorologists note that while rain showers can provide temporary relief by knocking airborne pollen out of the air, the resulting soil moisture often sparks fresh weed growth and higher pollen spikes in the days that follow.
READ: Strengthening ‘Super El Niño’ Forces Cut To Atlantic Hurricane Projections
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