Excessive Heat in Clay, South Dakota

Dangerous heat index readings reached afternoon peaks as high as 112 degrees at Vermillion and near Wakonda, and 108 degrees 7 miles west-southwest of Beresford.

A large high pressure system parked over the Mississippi River Valley, bringing several days of hot, southerly flow across the region. From the afternoon of June 28 to the evening of June 29, the combination of heat and humidity, boosted by recent rain, created dangerous conditions. Some heat index values exceeded 105 to 110 degrees in and near northwest Iowa.