Autumn colors in leaves of maple trees is an annual phenomenon that is highly prized for its beauty and is also economically important. As day length shortens, the tree stops making new green chlorophyll pigment while the chlorophyll already in the leaves breaks down. Without the green to mask it the yellow and orange carotenoid pigments become more visible. In some species like maples, red anthocyanin pigments are actively produced around this time. Research results suggest that the production of red pigments might help plants by protecting leaves while they reabsorb nitrogen before the leaves fall. There is no foolproof way to predict how the fall foliage season will progress. The intensity of color can depend on many factors but it is generally understood that cool weather creates the conditions that produce more vibrant colors but that freezing temperatures can cause those colors to fade. The weather on a given day can also impact the perception of color as well as the mix of species present and the topography of a particular location.