A common ragweed plant. (Photo by Uli Deck/picture alliance via Getty Images))As summer comes to a close, millions of Americans can reportedly expect the fall allergy season to be in "full force" this year.According to AccuWeather meteorologists, fall allergies are often triggered by ragweed and the presence of mold. "Fall allergies are typically triggered by ragweed, and the pollen from these types of plants that are common in North America can travel as far as the wind carries it," AccuWeather wrote.