Wisconsin El Niño winter; allergy season impact
MILWAUKEE - Allergy season brings irritating symptoms such as itching eyes, stuffy nose, sneezing, and sinus pain. This is something you may know all too well. Nearly 81 million Americans suffer from seasonal allergies to trees, grasses, and weeds.
In recent years, allergy season has been arriving earlier, becoming more severe, and lasting longer.
How does an El Niño winter affect people with allergies? To answer this question, we need to recap what an El Niño winter brings to the United States. An El Niño winter consists of warmer than average ocean water in the Pacific.
Warmer ocean temperatures during the winter months play a major role in how temperatures and precipitation play out across the United States. Due to El Niño, wetter conditions are forecasted for southern states, drier conditions in the Ohio River Basin, and warmer conditions are favored for northern portions of the United States-which includes Wisconsin.
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This winter will be the first El Niño in four years. In the past 40 years, there have been several El Niño winters. During three of the strongest El Niños, Milwaukee ranked in the top 15 warmest winters in the record books.
The stronger the El Niño, the warmer temperatures can be. The key for Wisconsin during El Niño is warmer than average temperatures-this is what can impact the length of growing season and allergy season. During all very strong El Niños in the past, 100% of the time we experienced 70-80 degree temperatures in March-which we normally don’t have until early April!
Evidence shows that warmer temperatures in winter and early spring along with longer periods of freeze-free days causes the first buds on plants to arrive earlier in the year. This elongates the growing season, so plants are blooming earlier in spring and hibernating later in fall.
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With more mild seasons ahead, vegetation can flower for a longer time or even multiple times a year. Warmer winter months can impact seasonal allergies by helping trees bloom earlier and potentially pollinate sooner.
There are three allergy seasons in North America-tree pollen season which occurs in the spring, grass pollen season which occurs in the early summer, and weed pollen & mold season which occurs in the summer/fall. With El Niño bringing warmer temperatures in the winter months, this could worsen tree pollen counts in 2024.
Dr. Gary Steven with the Allergy, Asthma, and Sinus Center collects pollen data every year. His data recorded high tree pollen counts and/or the earliest pollen sampling occurred during previous El Niño years.
Warmer temperatures from El Niño are only one of three factors that can cause trees to come out of dormancy and bloom earlier: They also need enough moisture during the winter/spring and enough daylight during the day.
Compare this to making a cake. You need all the necessary ingredients for it to bake. If you forget one, it doesn’t turn out well.
The same is true for trees. You need all three ingredients for buds to form. While there may be plenty of warmer days this winter due to El Niño, some tree species may or may not bud early due to the amount of light and moisture.
In Wisconsin, we typically see tree pollen in the air before trees even begin to grow. This is because trees flower earlier in warmer southern states. On days when there are strong southerly winds in late winter and early spring, pollen is transported north into Wisconsin, amplifying the tree pollen counts during allergy season.
So, with a very strong El Niño forecasted for this year, anticipate tree allergy season to be heightened, and more money spent out of your pocket to get relief from it.