![]() "The timing might not be the same, the colors might be a little bit more muted and not as beautiful and robust as we usually get to experience here in New England," as Nicole Keleher, the Massachusetts Department of Conservation and Recreation's forest health program director, told NPR member station WBUR. "Sunny, but not hot, days and cooler nights provide the optimal conditions for fall foliage, with the lower temperatures slowing the production of chlorophyll - the pigment that gives plants their green color - and sunlight increasing sugar production," according to North Carolina State University's College of Natural Resources.ĭry conditions in parts of the Northeast have experts warning that people may need to temper their expectations for the fall show. "We process hundreds of thousands of data points from a variety of private and government sources to accurately predict the precise moment fall will occur for the entire United States." The best conditions: cool nights and sunny days "Our model ingests multiple data points including NOAA precipitation forecasts, historical precipitation, average daylight exposure and temperature forecasts," Smoky Mountains founder and map creator David Angotti told NPR. But they say their map is based on a complex algorithm that generates a strong prediction. The folks behind the Smoky Mountains' map acknowledge that like any forecast, theirs might not prove to be 100% accurate for every area. "We see a forest that is healthy in the far north but increasingly stressed by heat and drought in the south and near the coast," Yankee magazine says in its report on the New England region. In areas where rainfall has been scarce, leaves could start changing color early this year, and their effect might be less vibrant. is coming off its third-hottest summer on record, according to the National Oceanic and Atmospheric Administration.ĭry conditions are another factor. The timing comes down to several weather factorsĪreas where warm temperatures persist can see fall colors arrive later than normal, especially if they've had near-average amounts of rainfall. But fall foliage can be very tricky to predict, especially as climate change brings warmer temperatures and disrupts historic rainfall patterns. will start seeing the most dramatic colors by late September to mid-October. The forecast produced by the Smoky Mountains website predicts much of the U.S. Fall colors usually peak from mid October into early November across central and southeast Illinois.Fall's dazzling colors will soon transform woods and forests around the U.S., delighting spectators - if they can figure out when to see the fall foliage at the peak of their transformation.Ī map of foliage patterns is here to help, offering a best-guess guide to when aspen, birch, larch and maple trees will turn vivid shades of gold, orange and crimson. Some trees across central Illinois begin to change colors during late September. When warm, cloudy and rainy weather dominates the fall season, leaves tend to have less coloration. Leaves directly exposed to the sun may turn red, while those on the shady side may be yellow. ![]() The degree of color may also vary from tree to tree. A few hard frosts can cause the leaves to wither and fall from the tree without changing color. The chlorophyll breaks down, the green color disappears, and the yellowish colors or other pigments already in the leaf become visible.Īutumn weather conditions favoring the most brilliant colors are warm sunny days and cool, but not freezing, nights. In the fall, the decrease in intensity and duration of sunlight, and the cooler temperatures, cause the leaves to stop their food-making process. The chlorophyll absorbs energy from sunlight, and uses it in transforming carbon dioxide and water to carbohydrates, such as sugars and starch. Change in coloring is the result of chemical processes, which take place in the tree as the seasons change.ĭuring the spring and summer, a food-making process takes place in the leaves, within cells containing the pigment chlorophyll. Leaves begin to turn before we have any frosts. ![]() Many people think that cold weather is solely responsible for the color change in leaves, but not so. Fall Colors across the United States - US Forest Service ![]()
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