The Eastern Deciduous Forest is a type of 'temperate deciduous forest.' These forests occur across the world in the mid-latitudes (between the tropics and the polar regions) in western Europe, eastern Asia, southwestern South America, and the eastern U.S. They are distinguished by warm and cold air masses that cause four distinct seasons a year. Trees change color and lose their leaves in fall as temperatures and precipitation levels drop. Winters have low precipitation levels and cold temperatures, and trees and other plants are inactive. In spring, temperature and precipitation levels rise causing plants to break dormancy and new growth and flowering to burst forth. In summer, plants of temperate deciduous forests grow the most, fueled by the warmest temperatures and highest precipitation levels of the entire year.