First Alert Weather: Allergy season now a month longer in Nashville, data shows

NASHVILLE, Tenn. (WSMV) — Seasonal allergies are becoming more severe for millions of Americans, including about one in five children, according to new data showing climate change is playing a direct role.

Warmer temperatures are creating more freeze-free days each year. That gives plants a longer window to grow and more time to release pollen that triggers sneezing, itchy eyes and congestion.

Growing season expands across U.S.

Researchers found the freeze-free growing season has lengthened in 87% of nearly 200 U.S. cities studied. On average, that is an increase of about three weeks since 1970.

In Nashville, the growing season has expanded by about 32 additional freeze-free days — more than a full month of extra time for plants to grow and produce pollen.

Pollen exposure extends across calendar

A longer growing season means more pollen over a longer period of time. Allergy triggers now include earlier spring pollen from trees, extended summer grass pollen and a longer-lasting fall ragweed season.

For those who suffer from seasonal allergies, the shift can mean more days with symptoms, stronger exposure to allergens and less time between peak pollen periods.