Air quality to worsen in Minnesota as dangerous heat continues

Tim Harlow, The Minnesota Star Tribune on Jul 15, 2026

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MINNEAPOLIS – A fifth day of dangerous heat comes with a new hazard: poor air quality.

Smoke from several wildfires burning in northern Minnesota and Ontario will continue sliding south Wednesday, bringing another reason to limit time outdoors, the National Weather Service said.

On Tuesday, the Minnesota Pollution Control Agency issued a maroon warning for the Arrowhead region of Minnesota, including the Superior National Forest and the Boundary Waters Canoe Area Wilderness as well as Lake, Cook and most of St. Louis counties.

Maroon is the highest and rarely used level on the agency’s six-level warning system. Heavy smoke reducing visibility was draped across parts of the Arrowhead on Wednesday morning, with unhealthy or very unhealthy air reported in Duluth, Proctor, Grand Marais and much of Cook County, according to AirIQ, an online air quality monitoring site.

Air quality alerts are in effect Wednesday through 11 a.m. Friday in the Arrowhead and across central and southeastern Minnesota, including the Twin Cities.

The good news is temperatures across northern Minnesota will sink into the 70s and 80s for the next few days after a string of 90-degree readings as well as 100 degrees in places such as Crane Lake on Monday, the National Weather Service said.

Smoke is expected to arrive in the Twin Cities on Wednesday and Thursday, and that could knock temperatures down a few degrees, but at least two more days of highs in the mid-90s are on tap. By Saturday, highs could drop to the low 90s, the National Weather Service said.

The unrelenting heat has led MnDOT to adjust some construction schedules, including on I-394. Crews will work from 7 p.m. to 6 a.m. through Saturday rather than during daytime hours as usual.

“We talk about safety concerns every day at MnDOT and heat is a safety concern,” spokeswoman Anne Meyer said. “We take breaks, and we provide hydration supplies. We also adjust some work sometimes and watch for any heat-related concerns.”

As cooler weather is poised to arrive next week in the Twin Cities and southern Minnesota — think highs in the low 80s — the Weather Service reminds people to practice heat safety and heed air quality warnings.

“Stay hydrated, check on the elderly and immunocompromised, and those without AC,” the Weather Service said. “Check the backseat of the car and limit time outdoors.”