Leaf-peeping season is underway, but some areas of the U.S. are seeing lots more color than others. Kyle Cotner, who owns The Foliage Report website, tracks fall foliage across the U.S. He says New England is having an elite year, thanks to adequate spring and summer rain, plus warm days and cool nights heading into fall. Colorado, meanwhile, is having a lackluster foliage season because of  extreme droughts. Fall foliage happens when leaves stop making the green pigment chlorophyll, allowing orange and yellow pigments that have been there all along to be unmasked. When sunny days are followed by cold nights, sugars get trapped in leaves, producing red pigments.