Fall Foliage Map 2018: When Is the Best Time to See Leaves Change Across U.S.?

It's that time of year again. Temperatures will soon get brisker and leaves will begin changing colors—but when and where should you be to see the leaves change?

A map from SmokyMountains.com predicted when the leaves will change in the fall of 2018 with an interactive map of the United States.

"Although simply entering rainfall, temperature data, elevations, and other data points into a model will never be 100% accurate, this combined with our proprietary, historical data drives our model to become more accurate each year," Wes Melton, co-founder and CEO of SmokyMountains.com said in an emailed statement to Newsweek. "However, unexpected rainfall that falls well outside of expected trends can always change the peak foliage dates and brilliance."

The team uses many data points to develop their map of the changing leaves including, National Oceanic and Atmospheric Administration historical and forecasted temperatures and precipitation. The group also examined when leaves peak historically and trends in peak leaf times. This helps the map predict the peak leaf observation time county by county across the country. They note that average temperatures are increasing, so with precipitation and weather patterns are changing, the brightness and length of the fall could be affected.

"Each year, we use a proprietary algorithm to process millions of data pieces and output accurate predictions for the entire country," Melton said. "Once the data is processed, the map outputs over 50,000 pieces of predictive data and then displays it on an interactive map."

Each year, the leaves change colors to red, purple, yellow and orange because of the chemical processes in the trees, according to the College of Environmental Science and Forestry at the State University of New York. The leaves make food for the tree during the spring and summer in cells that contain chlorophyll, which makes the leaves green. Chlorophyll absorbs sunlight and turns carbon dioxide and water into carbohydrates, like sugars and starch.

As the days get shorter and the temperatures get colder, the leaves stop making food for the tree. The chlorophyll will break down, causing the green leaves to turn. Carotene and xanthophyll pigments give leaves their yellow and orange color, and once the chlorophyll is gone, the leaves can then become those colors. Some leaves turn red and purple because of other pigments, like anthocyanin.

This fall, now you can track the changing leaves throughout the United States and plan when the best time would be to visit observation spots close to home or across the country.