You probably have noticed that green film on your car's windshield of late, and your nose may have also noticed it: one of the heaviest pollen seasons in New Jersey in recent memory, a so-called "pollen tsunami."

Andreas Rentz, Getty Images

Dr. Leonard Bielory, director of the Asthma and Allergy Research Center in Springfield, has his own term for this season, which he said is the most severe in at least 10 years.

"All of these trees are trying to pollinate at the same time," Bielory said. "That's a 'perfect storm.'"

He said springtime ushers in the arrival of grass pollen, which is the most common summer allergen. But before that even happens this year, early pollinating trees that laid dormant much longer than normal due to the overbearing winter -- like cedar, elm and maple -- have bloomed late, and are now about to give way to perhaps one of the strongest birch and oak pollen seasons in the last decade.

Pollen counts, already in the 4,000-plus range, will rise ever higher, though experts say the numbers still aren't unusually high. There is good news for allergy sufferers, though.

"It (the pollen count) will probably start fading more so by the third week in May, as the trees start to fade," Bielory said. "The elm, cedar and maple trees will fade in the next week, but the birch and oak will come to a peak."

For some who usually suffer only mild allergies around this time of year, Bielory said they may have more severe symptoms until conditions change later in the month. Those people are advised to check the pollen count every day and stay indoors as much as possible.