It won’t be long before the trees sprout colors of red, gold and orange as we march toward the official start of fall on September 22.

According to the Minnesota Department of Natural Resources (DNR), adequate rainfall nearly statewide, combined with lots of summer sunshine, point to a beautiful fall leaf season.

The DNR’s handy Fall Color Finder went live on September 7. Every Thursday throughout fall, people can consult the Fall Color Finder to learn more about peak fall color at www.mndnr.gov/fallcolors.

This tool comes courtesy of the DNR’s Parks and Trails Division and features:

A map that shows peak color across Minnesota.
A link to fall color programs and events.
A slideshow.
A photo uploader that provides a great way for sharing fall photos.

Rainfall and sunshine throughout the summer months determine the depth of color each fall in Minnesota. Kao Thao, a naturalist with Fort Snelling State Park, said that temperatures also come into play. An early freezing frost, for example, cuts short fall color.

“A light frost at the start of the color season actually helps produce vivid color,” Kao said. “During those summers when we experience a severe drought, colors are dulled somewhat. But we had plenty of rain and there’s always plenty of sunlight, so the leaf season at Fort Snelling State Park should be beautiful.”

Elsewhere the west-central and northwestern parts of the state saw less rain this summer than the metro area. Sometimes less rain, but not drought conditions, actually increase the color display.

All of the above begs a seasonal question often asked of the DNR. Just why do those leaves change color? Longer end-of-summer days and shorter bouts with sunshine as well as cooler nights trigger the color change. The most brilliant leaves show their hues after many warm and sunny days and cool nights.

Those shorter periods of daylight mean a closing off of the leaf veins that carry liquid sugar in and out of leaves. As a consequence, sugars in the leaf permit the red and purple colors to develop. Purple-like and red pigments are found in the leaves of maple and oak, some varieties of ash, and tall shrubs like cherry, sumac and viburnum.

Yellow is always present in leaves all summer long, but the color is revealed when the green pigment in chlorophyll breaks down. The yellow leaves, found in ash, aspen, basswood, birch, cottonwood and elm, may be short in lifespan due to drought conditions. If it’s dry, not as much sugar is produced so there isn’t as much color.

Check out a state park, recreation area, state forest, trail and water trail. Each is within viewing distance of beautiful leaf color. There’s a state park within about 30 minutes of nearly every town and city in the state. Find a state park at www.mndnr.gov/parkfinder.

As a general rule, colors typically peak between mid-September and early October in the northern third of Minnesota, between late September and early October in the central third of the state, and between late September and mid-October in the southern third, which includes the Twin Cities.

State park fall programs are listed in the 2017 “Programs and Events” sampler available at state parks and recreation areas, Twin Cities libraries, and at metro outdoor retail stores. The DNR Information Center will mail the brochure if requested. A listing of all fall programs can be found online at www.mndnr.gov/fallcolors.

For more information, contact the DNR Information Center at info.dnr@state.mn.us or call 888-646-6367 between 8 am to 8 pm Monday through Friday, and 9 am to 1 pm Saturday.

—Information by Minnesota Department of Natural Resources