Weekend rain officially classified as Minnesota's first 'mega-rain' event since 2016

The torrential rain that occurred in south central Minnesota over the weekend has officially been classified as a “mega-rain” event. 

The Minnesota Department of Natural Resources State Climatology Office said the storm “produced 6 inches of rain or more over an area of roughly 1,000 square miles,” from Saturday to Sunday, making it the first “mega-rain” in the state since 2016. 

The highest known rain total from the storm was 8.65 inches, which was reported by a human observer just south of Mankato. There were other totals of 8 inches of rain or more reported in the same area.  

Officials say there were also a number of reports of 6-7 inches of rain near St. Clair, St. Peter, Kasota, Morristown, Gibbon and Fairfax. 

RAIN TOTALS: More than 8 inches in St. Peter, less than 1 at MSP Airport

DNR’s automated rain gauges at Fort Ridgely State Park and Morristown recorded 7.77 and 6.37 inches respectively, although officials say those values are likely “under-catches” by up to 10 percent “because automated tipping buckets cannot keep up with intense rainfall rates.”

The State Climatology Office said totals closer to 10 inches may have hit an area with no observations, from southeastern Renville into southwestern Sibley County, according to radar estimates. 

Officials said there was little major damage from this weekend’s mega-rain, which is rare for these kind of weather events. 

“Most rains of this magnitude produce landslides, wash out roads and damage public and private property, but fortunately, this one came when river levels had been relatively low and when area soils had been in good condition after a mostly ‘normal’ summer,” the State Climatology Office said.