NASHVILLE, Tenn. (WKRN) — This is expected to be the longest and most aggressive seasonal allergy season due to the longer growing season.

The freeze-free season has been lengthened in 200+ U.S. cities by over two weeks on average since 1970.

Middle Tennessee’s growing season has been extended by approximately 25 days in the last 50 years. The more freeze-free days, the more time plants have to flower and release pollen.

The area is expected to have plenty of rainfall in the next few days, meaning pollen will be washed away—but you may notice a flare-up before that happens. When raindrops hit pollen, it can break them up into smaller pieces causing them to travel further before being washed away.

A quarter of adults, and 20% of children, will be affected by allergies this spring.

The different types of allergens

The three main types are airborne, pollen, and mold.

Airborne allergens are carried by the wind and can trigger asthma. Pollen is tiny grains released by plants and peak during the growing season. Mold is something dealt with year-round, but it grows in soil and on dead plants.

Different allergens affect everyone differently. Spring has sprung and it’s time to prepare for a long allergy season ahead.