Historic Mega-Rain Events in Minnesota
Minnesota is no stranger to heavy rain events. The early surveyors mapping out the state witnessed such events.
The DNR climate office has assembled a list of so-called "Mega-rain" events that have occurred since statehood. These are events where a six-inch area covers more than 1000 square miles and the core of the event topped eight inches. Using newspaper accounts, diaries, and the historical climate record, twelve such events in Minnesota's post-settlement history have been identified. Of particular note is that five of those twelve events have occurred since 2000.
There may be other events prior to 1972 that require further investigation such as September 11-15, 1903.
August 6, 1866 Southern Minnesota
Also known as the Wisel Flood, this event killed 16 people, including 3 members of the Wisel family in Fillmore County. 10.30 inches of rain fell at the Sibley Indian Agency located in Sibley County. The story of the Wisel family in peril appeared in the Harmony/Mabel/Canton News Record Newspaper from December 2011 to January 2012 in three parts:
July 17-19 1867 Central Minnesota
Estimated at 30-36 inches in 36 hours with at least 8 inches over a multi-county area. Known as Minnesota's greatest flash flood. Most of what is known about this event is from a paper that was read before the Minnesota Academy of Sciences on March 7, 1876. Climate Historian Tom St. Martin summarized the event as noted in newspapers of the time as well.
July 20-22, 1909 Northern Minnesota
Extensive flood event from Northwest Minnesota to the UP of Michigan. Highest one day rainfall total was 10.75 inches at Beaulieu in Mahnomen County (11.10 inches for the three day total.) This storm also did extensive damage in Duluth and killed two children in the city when they were swept out of their mother's arms.
September 9-10 1947, Iron Range
24 hour totals of 6 inches or more at Hibbing, Ely and Winton. Unofficial report of 8.60 inches in five hours at Hibbing. Extensive damage over the Iron Range district.
July 21-22, 1972 Grand Daddy Flash Flood
10.84 inches fell in 24 hours was set at Fort Ripley. This was the state record for a highest 24 hour total at a National Weather Service station until Hokah broke the record in 2007.
June 28-29 and July 1-2, 1975, Northwest Minnesota
Geographically extensive and intense rains fall on eastern North Dakota and Northwest Minnesota in two separate events.
July 23-24, 1987 Twin Cities Superstorm
June 9-10, 2002 Northern Minnesota
48 hour rainfall totals topped 12 inches in a some areas of Roseau and Lake of the Woods counties.
September 14-15, 2004 Southern Minnesota
More than ten inches of rain fell in a 36 hour period in Faribault and Freeborn Counties.
August 18-20, 2007 Southern Minnesota
The 15.10 inches measured one mile south of Hokah stands as the record 24 hour rainfall at a Minnesota National Weather Service Cooperative station. The three day total for this station was 16.27 inches.
September 22-23, 2010 Southern Minnesota
The National Weather Service site in Amboy measured 9.48 inches on September 23, with 10.68 inches for the event.
June 19-20, 2012 Northeast Minnesota
The two day total at Duluth was 7.24 inches. The St. Louis River at Scanlon set a new record crest at 16.62 feet, rising 10 feet in 24 hours.