THURSDAY, March 22 (HealthDay News) -- The unusually warm spring weather in New York and other parts of the eastern United States has trees and other plants blooming much earlier than normal, which could mean a long and intense allergy season.

Donald Leopold, chair of the environmental and forest biology department at State University of New York's College of Environmental Science and Forestry in Syracuse, said maples, willows, aspens, poplars and other woody plant species that bloom in early spring are major contributors of wind-dispersed pollen that causes allergic reactions.

Leopold is an expert in woody and herbaceous native and non-native plants.

On SUNY's campus recently, Leopold saw that an American elm was already producing pollen, a red maple was covered with male and female flowers, a row of spicebush shrubs had flowers of various sizes, and a native willow had bloomed early.

This is the first time in his 27 years at the college that he has seen these species bloom on campus before April 1, Leopold said in a university news release.

In short, all the signs point to an extended and severe allergy season.

With temperatures expected to reach the 80s in Syracuse, "things are really going to pop this week," he said.

More information

The MedlinePlus Medical Encyclopedia has more about hay fever.