Behind the Forecast: How weather influences Spring allergies

Listen to Science Behind the Forecast with Meteorologist Tawana Andrew every Friday on 89.3 WFPL at 7:45 a.m.
Listen to Science Behind the Forecast with Meteorologist Tawana Andrew every Friday on 89.3 WFPL at 7:45 a.m.
Published: Apr. 16, 2021 at 10:01 AM EDT
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Trees are starting to bud throughout the Heartland.  (Source: cNews/James Gullage)
Trees are starting to bud throughout the Heartland. (Source: cNews/James Gullage)((Source: cNews/James Gullage))

LOUISVILLE, Ky. (WAVE) - Allergies can be a year-round problem or seasonal.

After ranking number six out of 100 on the list of the worst places to live with seasonal allergies in 2019Louisville is now down to number 20 on that list for 2021. For seasonal rankings, Louisville was number 21 on the list of Most Challenging Places to Live With Allergies in the Spring and number 20 in the Fall.

More than 50 million Americans deal with allergies every year, according to the Asthma and Allergy Foundation of America (AAFA). One of the most common forms of allergies is allergic rhinitis, also called hay fever. Symptoms include:

  • Runny nose
  • Watery eyes
  • Itchy noses, eyes, or the roof of the mouth
  • Sneezing
  • Stuffy nose

Tree pollen is more of an issue in the Spring. It can start being an issue as early as January and last through July, according to AAFA. Since tree pollen is so small, the wind can carry it further. The following trees are most likely to contribute to seasonal allergies are:

  • Alder
  • Ash
  • Aspen
  • Beech
  • Birch
  • Box elder
  • Cedar
  • Cottonwood
  • Elm
  • Hickory
  • Mountain elder
  • Mulberry
  • Oak
  • Olive
  • Pecan
  • Poplar
  • Willow

In Autumn, ragweed pollen is the main source of allergens; ragweed is the most common pollen allergy.

Other plants that cause Fall allergies include:

  • Burning bush
  • Ragweed
  • Cocklebur
  • Russian thistle
  • Lamb’s-quarters
  • Sagebrush
  • Mugwort
  • Tumbleweed
  • Pigweed

Weather plays a big part in when and how much pollen is produced as well as how it is distributed.

Rain can bring joy and pain when it comes to allergies. Increased humidity and rain can weigh down pollen, keeping it from traveling. Rain can help to wash pollen out of the air and our environment. However, it can also help do distribute pollen. A burst of heavy rain can initially break up pollen particles into smaller pieces, pushing them into the air at a higher concentration and sending them out farther. Rain also helps to help plants grow which, in turn, means more pollen production. High humidity and rain help mold grow both inside and outside.

A lack of rain helps to slow the growth of plants and trees, reducing pollen production. However, hot and dry weather can help to bring mold spores out of the soil.

The wind moves pollen around and into our respiratory systems. Loose pollen is best dispersed on dry, windy days.

Warm weather helps to increase pollen counts while quick temperature drops can stop pollen production.

Plants with flowers or leaves may need more protection.
Plants with flowers or leaves may need more protection.(WAVE 3 News)

The weather well before Spring can impact our Spring pollen counts. A wet fall and winter can help to increase tree pollination in the Spring. A mild Winter that stretches into the Spring season can lead to trees and plants pollinating earlier and more than usual.

Each season has its own problems when it comes to pollen and allergies.

From February through April trees are the main issue. Mild winters can cause pollen to start pollinating in February! Once air temperatures are consistently above 50° trees will begin to pollinate. Colder temperatures can push pollination back to March or April.

Between May and June, grasses will begin to pollinate, continuing to do so through the summer. Grass pollen can sometimes last into July.

Weeds pollinate during the late summer and fall; July through October are the key months for weeds. Ragweed is one of the main weed allergens.

Trees and grasses are dormant from November through January. While outside allergens are not as much of an issue during this time, indoor allergens like mold spores and pet dander are more of an issue.

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