Intense summer drought may influence fall colors

Drought Influences Fall Colors
Published: Sep. 9, 2023 at 10:36 AM CDT
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ROCHESTER, Minn. (KTTC) – The autumnal equinox, or the official start of fall, is just two weeks away, and drought conditions have continued to intensify across southeastern Minnesota and northern Iowa. The dry conditions seen throughout this year could potentially affect the highly anticipated fall colors.

Meteorologist in Charge, at the La Crosse National Weather Service (NWS), Todd Shea said the drought across the region this year is harsh.

“ So, this is actually one of the most severe droughts in the region since about 2012,” Shea said.

On Thursday the latest update of the US Drought Monitor confirmed regions in southeastern Minnesota and northern Iowa are still underneath an extreme drought, while a portion overlapping Freeborn and Mower counties are at the exceptional level, which is the highest level of intensity.

In a fall colors press conference on Thursday, Kenneth Blumenfeld a Senior Climatologist with the Minnesota Department of Natural Resources (DNR) emphasized the state has previously experienced harsh drought conditions. He said this is the fourth consecutive year of having dry conditions during the growing season.

“Each of the last three years, has had extreme drought in Minnesota and now two of those years, 2021 and this year, have reached the exceptional category,” he said.

The La Crosse NWS reports from about mid-May until this week areas south of I-90 saw above-average temperatures and rainfall deficits around 7 to 14 inches.

“About mid-May on we started getting into these more stagnant weather patterns, where weather would go north or south of the region or we would go through extended periods of no precipitation at all,” Shea said.

Scientists at the DNR are not overly confident that changes can be seen in the fall colors this year based on previous droughts. Forest Health Specialist Brian Schwingle with the Minnesota DNR explained how droughts have affected the fall colors in the past.

" Fall colors diminished across the landscape, but not at a level that most people would notice,” he said.

Normally, the decrease in sunlight and chlorophyll are catalysts for fall colors.

“And as the tree stops making that chlorophyll pigments within the leaf that are already there like yellows, oranges, and brown pigments they’re unmasked,” Schwingle said. “They have always been there it’s just that there is so much green chlorophyll that it covers them up during the spring and summer,” he said.

If the heat from this summer continues then it could cause a change in the leaves. Right now, Blumenfeld said September is a transitional month, between seasons, and is the third fastest-warming month for the state because of past climate trends showing heat waves at the of the month. If the trees end up being stressed this fall from the drought you could see them lose color and drop off early.