In the Northeast, Southeast and Midwest, rain and heat have dominated this summer's weather. Unusually high amounts of rainfall have triggered the rapid growth of the number one fall allergen, ragweed.
"With a lot of rain and heat, ragweed has been growing like crazy," said Dr. David Shulan, partner at Certified Allergy and Asthma Consultants in Albany, N.Y.
Weeds, especially ragweed, produce the largest amounts of allergenic pollen, according to the National Institute of Allergy and Infectious Diseases (NIAID). These pollens can become airborne and drift for miles. Some samples of ragweed have been collected up to 400 miles out at sea and two miles high in the air, according to NIAID.
However, while rain in specific amounts can help ragweed grow, raindrops can also remove airborne allergenic pollens from the air, said Dr. Neil Kao, M.D., allergist and immunologist in Greenville, S.C.
After receiving significant rainfall this summer, the Northeast is predicted to have an average fall allergy season, but the weather in the Southeast and the Midwest created a perfect "sweet spot" for plants to grow, resulting in a higher predicted allergy season.
In the Southeast, "pollen seeds are growing and weeds are sprouting and places like South Carolina have higher pollen counts," said Kao. This summer's weather conditions have provided an ample balance of rain, sunlight and warm air, helping plants grow.
The Midwest will also experience an above-average fall allergy season.
"There will be lower levels of ragweed in the Northeast but the Midwest will be much worse," said Shulan. "Generally, in the Midwest, from Toledo and western Ohio to Chicago and Minneapolis, ragweed will be high."
Historically, the peak of allergy season for the South, including peak ragweed season, is around Sept. 19, with the four to five weeks before and after typically creating the time table for the worst of fall allergies. Although, late summer and early fall temperatures can slightly alter this timing, as the Northeast experiences peak allergy season around Labor Day.
"If it is warmer, then allergy season is later," said Kao. "Farther north, the date moves forward closer to Labor Day because temperatures tend to cool down faster."
Late September and October bring new threats to allergies with an increase in mold and dust mites as the air cools down.
According to AccuWeather Long-Range Forecaster Paul Pastelok, the East may have an overall mild September and October.
In late September, there could be a decent cold shot bringing an early season frost or freeze to the Midwest, and then more cold arriving in late October and November.
Cooler and damper fall conditions bring forth better conditions for mold and dust mites, other abundant allergens, to grow and prosper.
"In the North, people start closing up their houses up which is the breeding grounds for house and dust mites," said Kao.
While there are no cures for allergies, those who are prone to seasonal allergies can receive some relief by utilizing their air conditioning, using over the counter antihistamines, nasal sprays and eyedrops and seeking out a local allergist if allergy symptoms persist.