A Frost Advisory will be in effect early Tuesday morning for much of northeast Minnesota, excluding the North Shore, and for all of northwest Wisconsin.
Forecasted temperatures reaching 34 degrees or lower are expected to produce frost, with the most significant risk occurring in areas inland from Lake Superior.
No frost is forecasted for Tuesday morning near Lake Superior.
To date this month, both International Falls and Hibbing, Minnesota, have recorded minimum temperatures of 32 degrees or lower on two occasions. Historically, these locations experience an average of four such days in September.
Monday Morning Low Temperature Reports – September 21, 2026
Seagull Lake, MN: 29
Brimson, MN: 30
Hog Creek, MN: 30
Embarrass, MN: 31
Hibbing, MN: 31
Ely, MN: 32
Crane Lake, MN: 32
Cook, MN: 32
Ashland, WI: 33
Eveleth, MN: 33
Bigfork, MN: 33
Mountain Iron, MN: 34
South Range, WI: 35
Northome, MN: 35
International Falls, MN: 35
Superior Airport: 36
Nashwauk, MN: 36
Aurora, MN: 36
Hayward, WI: 37
Grand Marais Airport: 37
Isabella, MN: 38
Keewatin, MN: 38
Glidden, WI: 38
Maple, WI: 38
September 2026 is currently about 1 to 3 degrees warmer than the average for northeast Minnesota and northwest Wisconsin.
Precipitation totals so far this month have been above average in the green areas and below average in the yellow areas shown on the map below.
Later this week, light showers may touch the Northland on Thursday, while the Arrowhead and northwest Wisconsin stay mostly dry.
Today, a system has been progressing toward the east across Iowa while a new system moves across California.
Goes-19 water vapor loop for Monday, September 21, 2026, covering the period from 4:45 AM to 4:35 PM CT.
The system over Iowa has been generating showers today across southern Minnesota and southern Wisconsin, as well as portions of Iowa, Nebraska, and South Dakota.
Radar loop from Monday, September 21, 2026, loop time 6:12 AM to around 6:12 PM CT.
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