Why is pollen getting stronger and lasting longer?

(WVLT) -- Allergy season is on its way, and it's not going to be a pretty one, experts say.

Local allergy specialists are getting new patients and earlier in the year. Even in an area well-known for its pollen, this isn't just a trend.

"As we're seeing warmer, milder weather and lots of rain, we do see earlier seasons that are occurring in our region for sure,"

said Dr. Trent Ellenburg, of Allergy and Asthma Affiliates.

Ellenburg said their services are in such demand that they have expanded to eight clinics.

What's the cause? Dr. David Peden, with the University of North Carolina, said pollen season won't just be longer, the trees will make more people sick.

"They make more pollen, and they make more allergen, and so there's more pollen grains, and each pollen grain has more stuff that you are allergic to in it,"

he said.

An extra 10 to 20 percent of the population will suffer from allergies in a few decades, he added.

Dr. Joanne Logan, with the University of Tennessee, studies how plants are impacted by climate. Some of her climate logs go back nearly a century.

"The winter temperatures have definitely been milder, and I think that's causing the plants to break dormancy earlier,"

she said.

East Tennessee's growing season hasn't changed drastically. Knoxville's frost-free season hasn't moved more than a day or so since 1970, but in Nashville, they're staying above 32 degrees for almost a month longer.

The good news is that, while pollen can aggravate your allergies, Dr. Logan said allergy shots are the gold standard.

"It's about a 90 percent success rate,"

she said.