Tornado above on September 19, about 30 miles northwest of Duluth, MN.
Minnesota lies along the north edge of the region of maximum tornado occurrence in the United States, often referred to as Tornado Alley .
In Minnesota, tornadoes generally occur May through September, but some years see them occurring much earlier and/or later in the season. The record earliest-in-the-season tornadoes in Minnesota were the three that occurred on March 6, 2017, which broke the previous record from March 18, 1968, north of Truman in Martin County. The seasonally-latest reported tornadoes in Minnesota were on December 15, 2021 during a major regional severe weather outbreak (see image at right). This outbreak broke the previous record for late-season tornadoes by nearly one month; it had been November 16, 1931, when a single tornado struck east of Maple Plain in Hennepin County.
Historically and statistically, June is the month of greatest frequency with July not far behind. May has the third greatest frequency, followed closely by August. Over 85% of all tornadoes in Minnesota have occurred between May and August.
Tornadoes are most common between 2:00 PM and 9:00 PM, but can and do occur at any time of the day, or night.
Many of the deadly and damaging tornadoes occur in groups or outbreaks that often last from 3 to 12 hours. One of the worst such outbreaks in Minnesota occurred on June 17, 2010, when 48 tornadoes affected 22 counties in northwestern, west-central, central, east-central, south-central, and southeastern Minnesota over a period of six hours. Other noteworthy large-area outbreaks occurred June 16, 1992 (which included the state’s most recent F5 tornado, in Chandler); June 28, 1979, when 16 tornadoes slashed across the state from northwest to southeast; August 6, 1969, when powerful and massive tornadoes devastated parts of northern Minnesota; and the April 30, 1967 “Black Sunday” outbreak in southern and southeastern Minnesota.
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Below, a chronicle of the December 21 outbreak across the midwest.