Longer growing seasons may mean longer allergy seasons

By Allison Finch,

Spring is creeping up fast in the United States, and that means warmer weather is on the horizon after a rough end to winter in some locations. Still, for those who suffer from seasonal allergies, there may only be a few weeks left in some parts of the country before allergens kick into full gear.

A team of AccuWeather forecasters, led by senior meteorologist Alan Reppert, took a deep dive into forecast data, weather patterns and climate research to forecast what the fast-approaching allergy season will be like -- and if there will be an extended or higher-than-usual pollen season.


According to Climate Central, a nonprofit science and news organization based in Princeton, N.J., recent research suggests that the growing seasons are being lengthened by more than two weeks compared to the historical average since 1970. This could prolong the symptoms many seasonal allergy sufferers endure.


The first leaves and spring blooms are arriving in parts of the United States, according to the USA National Phenology Network. The network, which tracks the onset of spring across the country, says much of the Southeast, lower Midwest and mid-Atlantic states are experiencing the earliest spring on record. But for some locations in the Southwest, such as Arizona, spring is a bit delayed compared to the historical average.

Different allergens will begin to affect Americans at various points in the season, depending on the region and the weather conditions. According to Reppert, trees are commonly the first and most prominent producers of pollen in the spring. By late spring and early summer, grass pollen will start to dominate and finally, toward the late summer and early fall, weed pollen will take over for the rest of the season.

The weather plays a crucial role in how much pollen is produced, distributed and in the air at any given time. When determining if the pollen levels will be high, average or low, one must consider important factors like rain, wind and temperature.

On warm, windy and dry days, pollen has an easier time circulating, which can increase allergy symptoms. Pollen tends to travel less on rainy, windless days, which can benefit those who suffer from allergies. Dry conditions and drought can reduce certain pollen levels and hinder grass and weed growth.


Reppert's team of meteorologists has put together a comprehensive analysis for the allergy season ahead. The forecasters warn that one particular part of the United States may be more susceptible, than others this year.

Tree pollen has started to peak across much of the Southeast and Gulf Coast states due to unusually warm weather surging in these regions. Since the end of February, temperatures have been above historical averages, which has prompted an earlier start than usual for many areas across the South.

According to the USA-NPN, Charlotte, N.C., is experiencing a spring bloom 22 days earlier than normal.

Despite the rain being a great pollen reducer, sometimes lighter rain showers don't contain enough moisture to clear the air of all the pollen. And according to Reppert, the multiple rounds of rain expected across the Southeast and Ohio River Valley through the end of March won't be enough to ease the high pollen levels for allergy sufferers.

In the Northeast, an earlier start to the tree pollen season will be likely, but Reppert warns temperatures cooler than the historical average this spring will give way to an average season from the Appalachian Mountains to Maine.

As temperatures struggle to increase this spring and rainfall chances decrease across the northern Plains, a lower-than-average tree pollen season is expected from Nebraska to North Dakota.


Tree pollen is expected to be the worst in the Pacific Northwest this year. For allergy sufferers living in this region, limiting the amount of time spent outside this spring may be a good idea. Reppert said moderate temperatures and rainfall will provide ideal conditions for trees to grow and little time for pollen levels to drop.

From south to north, pollen levels will start to increase as early as the beginning of April. By the end of April, tree pollen levels are expected to be at their worst in the Pacific Northwest.

In contrast, across the Rockies, tree pollen should be on par with what is considered average for the region.

Southwest residents with tree allergies will be able to rejoice. Thanks to an upcoming drier weather pattern and warmer air on the horizon, tree pollen counts in the region are expected to remain low throughout the season from southeastern California to western Texas.

Grass pollen sufferers from the Great Lakes to the Gulf Coast may want to start preparing for what is expected to be a nasty allergy season for many. Above-normal grass pollen levels are forecast to extend across the eastern third of the country this year. Ohio, Virginia, Tennessee and Mississippi will be among the several states that will have some of the highest grass pollen counts in the nation this year, Reppert warns.


Reppert said grass pollen levels will surge due to expected warmth and above-average rainfall late this spring and early this summer across the East. He also warns that this region's peak values will be earlier than usual.

Grass pollen levels will peak across the Gulf Coast states by early to mid-May. The mid-Atlantic and Ohio Valley states will experience their peak by the end of May. Pollen levels in areas farther north, such as the Midwest, will peak by mid-June.

One place across the East that won't have above-average grass pollen levels in the Northeast. According to Reppert, temperatures there should align with levels typically observed in spring and summer. This is due to a surge in cooler temperatures and a rise in moisture during the second half of summer for the Northeast.

From southern North Dakota to the Four Corners, grass allergy sufferers are in luck this year. Reppert says the combination of drier weather and the delay of warmer weather will result in low grass pollen levels this year.

The grass pollen season will peak in Arizona, New Mexico and western Texas before the middle of May, while residents in areas farther north, such as the Rockies and northern Plains, won't experience their peak until the end of May or the beginning of June.


The dry season in the West starts in May and continues through September. In years past, drought conditions typically lead to a lower-than-average season for this region. Due to several atmospheric rivers that brought significant amounts of rain and erased the drought across much of the West, Reppert said grass pollen levels are expected to be near normal this year.

As for the Pacific Northwest, allergy sufferers are in for a double whammy. In addition to a record-high tree pollen season, forecasters expect above-average grass pollen levels across the region.

Reppert notes that grass pollen will flourish this summer after the relentless rounds of rain in the winter and early spring. Temperatures above historical averages this summer will also favor higher grass pollen counts.

In addition to those living along the East coast, residents in metropolitan areas like Seattle and Portland, Ore., could experience some of the worst grass pollen levels this season.

Weed pollen is a late-season pollen that notoriously affects Americans before cold winter weather settles back into the north and the sun dips below a certain angle in the south.

According to Reppert, weed pollen will dominate the entire East Coast as an increase in moisture and temperature creates a favorable environment for weeds to thrive.


"It's really going to increase here as we get into September, and any tropical moisture that may come into the area or any storms that come in over the plains and from the north, that could really help to increase any of the weed pollen that we're seeing," Reppert said.

Across the Gulf Coast and Southeast states, weed pollen is expected to pick up later than usual, peaking from late July to mid-August. Weed pollen will flourish from mid-August to early September in the mid-Atlantic and Ohio Valley. As for the Northeast, pollen levels aren't expected to peak until after September gets underway.

In contrast, weed pollen is forecast to be lower than normal across the northern and even parts of the central Plains. Reppert explains this is due to the lack of wet weather across the northern Plains.

Weed pollen levels are expected to be on par with previous years across the southern Plains, he said.

In the southern Rockies and parts of the Southwest, such as Texas, southern New Mexico and southeastern Arizona, drier conditions are expected to influence weed pollen counts. According to AccuWeather forecasters, these areas will likely have pollen counts below normal.

A different story is in the forecast for the northern Rockies, however. Projections call for a long and potentially arduous season ahead as weed pollen levels are expected to be consistently above average from Colorado to Idaho this year.


According to Reppert, weed pollen levels will peak in the Rockies during the late summer and early fall months. As for the West Coast, weed pollen levels should be on par with what is considered average for the region.

"The weather and allergy season go hand in hand," allergist and medical director of Allergy and Asthma Care of New York Dr. Cliff Basset told AccuWeather in an interview.

Basset said more than 50 million Americans are affected by seasonal allergies yearly. Knowing when allergy levels will be high and having a plan will be a "game changer" for many. Just like people check the weather before getting ready for the day, Bassett recommends allergy sufferers check the pollen count before heading out the door in the morning.

"I always say live with Mother Nature, enjoy all the benefits, but do it wisely," he said. "Always check your weather and check your pollen count to know what the pollen count is near you."

The Asthma and Allergy Foundation of America puts together a report every year of the most challenging place to live with allergies for the season ahead. According to the 2023 allergy capital list, released on Wednesday, Wichita, Kan., is expected to be the most challenging place to live this year for allergy sufferers.


The report looks at tree, grass and weed pollen scores, availability of board-certified allergists or immunologists and use of over-the-counter allergy medicine to determine the scores for each city.

Since the start of the COVID-19 pandemic in 2020, a layer of complexity has been added to the seasonal allergy season. For those trying to determine if their symptoms are from seasonal allergies, the common cold, the flu or COVID-19, Basset said there is one telltale sign of allergies that the other illnesses don't have in common.

"One of the most common symptoms [of allergies] is the letter I -- itchiness. Itchiness of eyes, nose and throat," Basset said. "If you have a viral infection or flu or even COVID, taking allergy medications such as [an] antihistamine [or] nasal steroid sprays is not going to fix the problem."

If seasonal allergies bother you, Basset recommends talking to your doctor about how you can develop a plan to combat the pesky allergens each year.

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