If you get springtime allergies, chances are they haven't been too bad this year. But that's about to change. Allergists say we're on track for one of the worst allergy seasons in years.

Already, allergy sufferers in the U.S. South and Northeast are contending with itchier-than-usual itchy eyes, and sniffly-than-usual sniffly noses.

The Asthma and Allergy Foundation says the worst of it is in the Deep South, with Knoxville, Tenn., Louisville, Ky., and Charlotte, N.C. among its "2011 spring allergy capitals," based on airborne grass, tree, weed pollen counts, and other measures.

In the northeast, Chicago has seen its highest tree pollen count in three years in the last week.

"It's been a very bad season so far," Dr. William Reisacher, director of the allergy centre at New York-Presbyterian/Weill Cornell Medical Center in New York City, told the Associated Press earlier this week.

"A lot of people who haven't suffered in previous years have come in for the first time in several years with symptoms.

It's all because of an early spring with plenty of rain which has caused a profusion of growth in allergy-causing plants and trees. The sudden shift to warm, sunny weather south of the border in recent weeks has allowed pollen counts to go sky-high.

Here in Canada, most parts of the country have seen plenty of rain too, but temperatures have remained stubbornly cool. But once the familiar heat of summer kicks in, there could be an explosion of pollen, experts warn.

Ontario allergist Dr. Harold Kim, who sits on board of the Canadian Society of Allergy and Clinical Immunology, says people with mould allergies are already suffering.

"I can tell you anecdotally, in my area, in Kitchener, we've seen a lot of patients with quite severe asthma, which is from mould," Kim told CTV News Channel Wednesday evening.

He said while tree and grass pollen counts have remained low, that will change.

"Once the temperatures rise, because it has been so damp, I think we are going to see quite a peak in tree pollen seasonal allergies and then after that, grass pollen."

Kim and other experts say allergy sufferers in the thick of their symptoms have a habit of insisting that each year is the worst one ever. "And that's partially because people forget about their allergies during the winter," says Kim.

But this year, they might actually be right.

New York allergist Reisacher says it's possible that medications that allergy sufferers have used in the past may not be as effective this year. Many of his patients have required multiple drugs, including nasal sprays, oral antihistamines and eye drops, he reports.

To add to the misery: Experts say the allergy season across most of Canada is growing longer thanks to climate change.

Plant and allergy experts with the U.S. Department of Agriculture completed a study earlier this year in which they analyzed ragweed pollen counts from Texas to Saskatoon over a 15-year period. They found that ragweed now has a longer flowering season that extends further north than it did years ago.

The study authors say the pollen season has been lengthening due to an increase in the number of frost-free days and a delay in the first autumn frost.

Five sites that they looked at, from Wisconsin north to Saskatoon, saw significantly longer ragweed pollen seasons of at least 13 days. And the further north they went, the longer the pollen season had extended.

Saskatoon's season, for example, is now 27 days longer than it was 15 years ago. That's about a full month more of sneezing, wheezing and watery eyes.