The variety of harsh weather in recent weeks across the state might make one think Minnesota’s fall colors story has been written.
On the contrary, our state story is still mid-chapter.
Evidence is on the Fall Color Finder web page, the Department of Natural Resource’s tool online to track fall foliage, with weekly updates on which parts of the state are in transition or peaking. Almost half the state was at 75-100 percent peak color Wednesday, with the metro and areas to the south at 50-75 percent.
Undeniable evidence is the science of the season, and how a combination of temperature, sunlight and moisture contribute to what naturally occurs as our days shorten: Leaf chlorophyll production will dwindle, giving way to other pigments in the leaf — the scarlets of red maple, rich yellows in aspen and poplar, oak-red, and on.
Bottom line: Fall colors, like so many paints in an artist’s pallette, are still having their moment. And while those vibrant red leaves in some areas might leech some of their color owing to heavy rain, from the science angle, moisture currently isn’t so much a factor.
“We need sunlight, and we just haven’t had it,” said Val Cervenka, a forest health specialist in the Department of Natural Resources. Cervenka has given the official state fall color forecast since 2010, and remains upbeat on the 2018 version.
A string of sunny days in the 50s, with cold nights above freezing — what’s regarded as authentic fall weather — are what it takes. And the recent forecast has been suitable for our mixed woodlands. That combination of temperature and light helps trees produce sugar. Trapped by cool nights, the sugar and light in a leaf produce red and crimson pigments shown in the photos with this story by Star Tribune photographer Brian Peterson.
What’s moving areas of the Superior National Forest on the North Shore “past peak” are high winds and in places snow that are stripping leaves, according to a fall report from the U.S. Forest Service. Still, birch and aspen have yet to fully peak in some stretches, and they tend to hold on longer than maples.
Judging by the tracker — and experience — Cervenka said Minnesota’s trees and shrubs have a lot left to show. “People might be surprised,” she added.