Here's some good news for fall outdoor enthusiasts: During the next eight or nine weeks, breathtaking fall colors will blanket Minnesota's forests and prairies thanks to adequate rainfall nearly statewide and lots of summer sunshine.

Kao Thao, a naturalist with Fort Snelling State Park, said that temperatures also play a role. "A light frost at the start of the color season actually helps produce vivid color," Kao said in a statement. "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."



Even though the west-central and northwestern parts of the state saw less rainfall this summer than the metro areas, they too could experience a vivid color display.

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.



Why do leaves change colors in the fall? But why do those leaves change color? Longer end-of-summer days and shorter bouts with sunshine, as well as cooler nights, trigger the change. The most brilliantly colored leaves show their hues after many warm and sunny days and cool nights.



Shorter periods of daylight mean a closing off of the leaf veins that carry liquid sugar in and out of leaves. Consequently, sugars in the leaf allow the red and purple colors to develop. Red and purple-like pigments are found in maple and oak leaves , some varieties of ash leaves, 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 experience shorter lifespans due to drought conditions in which not as much sugar is produced and colors are duller.



But when will the leaves in your area will change? You can't know precisely, but an interactive map can help you predict when to take your fall foliage tours and see the leaves at their vibrant peaks.