The Deciduous Forest biome has four distinct seasons; spring, summer, autumn, and winter. Its mild summers average around about 70 degrees fahrenheit. The average temperature in the deciduous forest is about 50 degrees F. The average amount of rainfall in the forest is 30 to 60 inches a year.As the seasons change, so do the colors of the leaves of the deciduous. During the winter months water is generally not available to keep the leaves of some plants alive. So the leaves of some plants fall off and grow back in the spring.he average amount of rainfall in the forest is 30 to 60 inches a year. As the seasons change, so do the colors of the leaves of the deciduous. During the winter months water is generally not available to keep the leaves of some plants alive. So the leaves of some plants fall off and grow back in the spring.