How Can Weather Help or Hurt Seasonal Allergy Sufferers?

As the weather changes, there are also changes in the patterns of major allergy triggers.

"Throughout the world, trees pollinate in the spring, grasses pollinate in the summer generally and then it's weeds' turn in the fall," Senior Vice President of External Affairs at the Asthma and Allergy Foundation of America (AAFA) Mike Tringdale said.

This difference in pollination seasons causes people to have a reaction to allergens during different times in the year based on their specific allergies.

"Allergens that cause disease in humans fall into four categories: dust, mold, pollen and animal dander," Dr. Neil Kao M.D., allergist and immunologist in Greenville, S.C., said.

According to the AAFA, an estimated 40 million Americans suffer from outdoor allergies because they are allergic to pollen.

Loretta McConegy, from the Asthma and Allergy Research Center at the University of Medicine and Dentistry of New Jersey Newark, points to the pollen on a ragweed plant in Newark, N.J. Tuesday, Aug. 14, 2001. With ragweed plants flourishing after recent heavy rains, the late-summer hay fever season will be tormenting allergy and asthma sufferers very soon. (AP Photo/Daniel Hulshizer)

Pollen can get transferred either by the wind, or by insects and birds. Ragweed and other common pollens that cause allergic reactions rely mainly on the wind to carry them from plant to plant.

"People generally aren't allergic to flowers in their garden, to roses or tulips, because those are insect and bird pollinated," Tringdale said. "That pollen is not meant to be blown by the wind."

Wind-blown pollens are very aerodynamic and can end up being deposited up to 500 miles from its original source, according to the AAFA.

Pollen is most likely to spread during times when the weather is warm, dry and windy, because the more the wind blows, the more pollen can get carried in it, according to Kao.

In addition to wind, sunlight and water also play an important role in the dissemination of pollen. Plants that get more sunlight, moisture and nutrients can grow bigger, and produce more pollen for the wind to pick up.

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Heavy rain might be thought to greatly reduce pollen counts in the area by washing it away, but it is actually just the opposite.

"Rain can push pollen from the trees, but unfortunately it doesn't necessarily wash it away," Tringdale said. "That pollen dries up on the ground now and becomes airborne."

Since the pollen gets shaken loose from the trees and becomes airborne, one of the most difficult times for people with allergies can actually be after a rainstorm.

Hurricanes and other severe weather events can bring a lot of moisture to areas where it normally isn't very wet. This can contribute to higher mold growth, and can cause plants to grow bigger and pollinate more in areas you wouldn't expect, according to Tringdale.

Weather can also impact allergies in the long term. As weather patterns are changing, pollinating and allergy seasons are expanding.

"Spring and summer are starting earlier and lasting longer, and you have these pollinating seasons that are lasting longer too, meaning that people's allergy seasons are getting longer," Tringdale said.

In addition to impacting how allergens are spread, the weather can also exacerbate existing allergy conditions. High air pressure or cold air can cause bronchial tubes to constrict, and sinuses and throats to inflame.

If you have bad outdoor allergies, you should avoid spending too much time outside, especially when it is windy.

"The longer you are exposed and the more you breathe in, the more you are going to pay for it," Kao said.

By Staff Writer Rachelle Gaynor

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