Pollen forecast to reach levels higher than the historical average across 39 states this year
Pollen counts are expected to be higher than the historical average across parts of 39 states this year
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AccuWeather Global Weather Center – March 19, 2025 - AccuWeather expert meteorologists are urging people living with seasonal allergies to prepare for an intense allergy season that could last longer into the fall months.
Pollen counts are forecast to spike at levels higher than the historical average at times across parts of 39 states.
"About 1 out of every 4 adults and nearly 1 in 5 children have been diagnosed with seasonal allergies in America. Millions of people living with seasonal allergies will be struggling with more intense symptoms that will likely stick around longer this year in many areas,” AccuWeather Senior Meteorologist and Allergy Expert Alan Reppert said. “You can blame wet and warm weather patterns expected later this year for pollen levels that will reach levels higher than the historical average in many places.”
Impacts from a late frost and chilly spring
Areas in the Northeast and Great Lakes that experience a late frost and a later start to the growing season will see lower tree pollen levels this spring.
AccuWeather expert meteorologists say the last frost of the season may arrive later than the historical average in parts of northeastern Georgia, western South Carolina, as well as southern and central North Carolina. Cooler air will slow tree pollen production.
Tree Pollen
Tree pollen is the first of three primary allergens in the United States that can cause sneezing, nasal congestion, stuffiness, itchy eyes, a sore throat, wheezing, skin reactions, and sinus pressure for allergy sufferers.
Tree pollination begins in the spring after ground temperatures rise to 40-45 degrees following the winter months, followed by a wave of grass pollen in the late spring and early summer, and then weed pollen that arrives in the late summer and fall months.
AccuWeather expert meteorologists say tree pollen levels are expected to be higher than the historical average this year across a 2,000-mile-long zone from the Gulf Coast to the Northwest spanning 22 states.
Tree pollen levels have already peaked this year across much of the South and Gulf Coast states.
A cooler start to spring across much of the East is expected to keep tree pollen levels lower over the next few weeks, but very high levels are possible later this season.
“Tree pollen levels are expected to hover around average levels in the Northeast, but there could be a one-week period when higher temperatures and a lack of rainfall may send tree pollen spiking at high levels,” Reppert said.
High pollen levels are expected through most of spring in the northern Rockies and Pacific Northwest.
The tree pollen season started early in the Southwest, but drier weather will likely bring an early end to the season.
Grass Pollen
Allergy sufferers in much of the Northeast and mid-Atlantic should prepare for a summer with higher grass pollen levels compared to the historical average.
"Grass pollen starts as tree pollen starts to wane and can begin along the Gulf Coast as soon as April when grass starts to grow," Reppert said. "It can last through the summer and into the early fall before the sun angle starts to decrease low enough or a frost occurs."
AccuWeather expert meteorologists say warm air and plentiful rainfall expected in the Northeast and mid-Atlantic will allow grass to grow quickly this summer.
High grass pollen levels are also anticipated across parts of the Northwest this summer.
Dry weather expected this summer will keep grass pollen levels low in parts of the Southeast and eastern Gulf Coast.
Weed Pollen
The highest weed pollen levels are expected across the coastal Carolinas, over the southern Plains and across the Gulf Coast this year.
AccuWeather expert meteorologists say increased rainfall and additional moisture from tropical storms and hurricanes could extend the weed pollen season in both regions.
Weed pollen is expected to peak in July across the Tennessee Valley. Reppert says a second weed pollen peak is possible this year with an increase in rainfall likely in late August and September.
"Weed pollen contains thistle, sagebrush and mugwort, and much like tree pollen, these have different start times through the weed pollen season," Reppert said.
Lower weed pollen levels are anticipated across the Northwest due to drier weather this summer and early-season colder air that could kill weeds early in the northern Rockies and Pacific Northwest.
How our warming climate is impacting seasonal allergies
Following a colder and snowier winter across much of the country compared to recent winter seasons, AccuWeather long-range experts predict spring temperatures to be warmer overall than the historical average across much of the western, central, and southeastern U.S.
AccuWeather Senior Meteorologist and Climate Expert Brett Anderson says AccuWeather’s 2025 U.S. Spring Forecast is consistent with the trend of warmer spring seasons in America, creating longer growing seasons and an earlier start to the allergy season.
“Many allergy sufferers have noticed their symptoms worsen over the past decade. The trend of more intense allergy seasons getting a jump start earlier in the spring and lasting later into the fall follows the overall trend line of warmer and wetter spring seasons in America,” Anderson explained. “There will be variability year to year depending on spring temperatures, storm tracks, and additional moisture from tropical storms and hurricanes, but the overall trend is clear. Pollen counts are on the rise and seasonal allergies are getting worse for millions of people as our climate continues to warm.”
Anderson says the seasonal allergy season is lasting one to four weeks longer in many parts of the country, compared to 50 years ago. The trend of longer and more intense allergy seasons is expected to continue over the next decade.
“The burning of fossil fuels releases carbon dioxide into the atmosphere, contributing to the greenhouse effect that is warming our climate. As more fossil fuels are burned around the globe, rising carbon dioxide levels are contributing to increased pollen production,” Anderson said. “Warmer air can hold more moisture. The combination of more rainfall that can boost plant growth, higher spring temperatures, longer growing seasons, and more carbon dioxide in the atmosphere triggering increased pollen production is the reason why more people are experiencing seasonal allergy symptoms for the first time, and many longtime allergy suffers are dealing with worsening symptoms.”
How to combat seasonal allergies
Reppert says there are simple routines and best practices to help keep seasonal allergy symptoms in check.
In addition to talking with your doctor or allergy specialist about over-the-counter treatment, prescriptions, or allergy shots, people living with seasonal allergies are encouraged to avoid outdoor exercise and activity in the early morning hours. Pollen levels are often highest just after sunrise.
It’s best to keep windows in your home and car closed and to regularly change air filters as recommended by the manufacturer.
After spending time outdoors, Reppert recommends changing your clothes immediately and showering before the end of the day to prevent bringing pollen into your bedroom. It’s also recommended to wipe down furry pets after they’ve been outside during high-pollen days.
Reppert also says to check the forecast on the AccuWeather app before planning outdoor activities. Pollen tends to kick up more during warm, windy and dry weather.
Rain can help clear pollen out of the air, creating windows of low pollen levels after heavy rain or downpours.
Tree pollen, grass pollen, and weed pollen reports in your area are available for free on the AccuWeather app and AccuWeather.com, along with the health and activates outlook and the air quality report powered by Plume Labs, an AccuWeather company.
