Barneveld–Black Earth, Wisconsin

As the tornado activity calmed down across Iowa and Minnesota in which numerous strong to severe tornadoes struck those areas from mid-afternoon to mid-evening, the severe weather shifted east towards Wisconsin after dark where a tornado watch was issued at about 11:00 pm CDT. By this time, most of the residents of Barneveld had gone to bed and were unaware of the tornado watch. A supercell thunderstorm, which affected portions of southeastern Iowa with a few tornadoes at around 9:00 pm CDT before weakening and intensifying shortly after, entered Wisconsin from the Iowa/Illinois border at around 12:00 am CDT near Dubuque. Shortly after 12:30 am CDT, June 8, it produced its first tornado near Belmont in Lafayette County and lifted near Mineral Point in Iowa County about fifteen miles southwest of Barneveld.

A few minutes later, this storm system produced one of the few F5 tornadoes to hit Wisconsin, developing northeast of Mineral Point (five to six miles southwest of Barneveld). At 12:41 am CDT this F5 tornado drove through the center of Barneveld in full force, finally dissipating in northern Dane County around 1:40 am CDT after traveling 36 miles (58 kilometers) for 59 minutes.^[5] A strong lightning strike cut the electricity to the town just a few minutes before the tornado struck Barneveld, but it was followed by a deafening clap of thunder that awakened many residents. (It is said that the loss of power prevented the tornado siren from being activated prior to its arrival; in actuality, the town did not have a tornado siren that differed from the siren used to activate the town's volunteer fire and EMT squad. If the siren had been activated, the residents would not have known it was a tornado warning.) At its peak, the tornado was nearly a quarter-mile wide. Other tornadoes rated from F1 to F3 touched down from Columbia County to Dodge County until after 3:00 am CDT when activity finally weakened.

The tornado was responsible for nine deaths and nearly 200 injuries in Barneveld while causing about $25 million in damage. In total, all three churches (the Congregational United Church of Christ, the Lutheran Church, and the Roman Catholic Church), 93 homes and 17 out of the 18 businesses in town (including the library, municipal building, fire station, bank, and post office) were all destroyed. The village's water tower, though damaged, was not toppled by the winds. In addition, 64 other homes were badly damaged. The F5 damage occurred at a cul-de-sac on the northeast side of town. A cluster of newly built homes were completely swept away at this location. Trees were debarked and vehicles were thrown and mangled.^[6] Some of the debris including paperwork was later found about 135 miles away from the village. Eight homes were also destroyed in Black Earth, and 24 additional homes were destroyed between Barneveld and Black Earth. Other tornadoes in Wisconsin caused two additional injuries and about $15 million worth of damage but no additional fatalities.^[7][8]

The National Weather Service in Madison reported the next day that the frequency of lightning flashes in the storm exceeded 200 per minute. The flashes produced a strobe-like effect, as mentioned in media reports and books about the disaster.^[9]