Behind the Forecast: Why grass allergies are worse when it’s hot

LOUISVILLE, Ky. (WAVE) - We’re well into Spring, and allergy season is in full swing. Now that the trees have done their thing, it’s time for grasses to become our primary pollen source.

In May, grass pollen starts to show up in counts and continues to be the main culprit through the summer months. While grass pollen is usually an issue into July, sometimes it may stick around through August and September. Poaceae grasses include Kentucky Bluegrass, Bermuda, Redtop, Timothy, and Orchard.

Kentucky Bluegrass germinates when the soil temperature ranges between 50° and 65°, according to experts; this corresponds to daytime highs between 60° and 75°. Most grasses pollinate the most when it is hot; that’s why grass allergies are often worse in hotter months. Grass pollen grains are minuscule and can be carried hundreds of miles by the wind.

The Asthma and Allergy Foundation of America put out their 2022 ranking of Allergy Capitals across the United States, and once again, Louisville is in the top 50. Overall, Louisville ranks 43 out of 100 cities. Last year, Louisville sat in the 20th spot, and in 2020, Louisville ranked 22nd.