While parts of the 2023 summer had warm to hot temperatures, it took until middle to late August for the combination of hot temperatures and higher humidity levels to build a heat wave. Excessive heat advisories and warnings were initially issued on Tuesday, August 22nd and lasted through Thursday, August 24th. Heat indices reached and exceeded 100 degrees each day, with overall highest heat indices occurring on Wednesday, August 23rd. During this time, maximum daytime heat indices reached 118 degrees at Rochester (Olmsted County), Hokah (Houston County), and La Crescent (Winona County). Many sites in southeast Minnesota recorded heat indices of 105 to 120 degrees over the three days from August 22nd to August 24th. The excessive heat resulted in cancelled events in Rochester (Olmsted County).

Excessive Heat in WABASHA, MINNESOTA
From 22-AUG-23 11:00:00 to 24-AUG-23 20:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

The combination of anomalously high temperatures and humidity on Tuesday, August 22nd and Wednesday, August 23rd resulted in maximum heat indices of 112 to 117 degrees in parts of Wabasha County. The maximum heat index reached 115 degrees on Tuesday and 117 degrees on Wednesday at the automated weather observation station in Lake City.

Excessive Heat in HOUSTON, MINNESOTA
From 22-AUG-23 11:00:00 to 24-AUG-23 20:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

The combination of anomalously high temperatures and humidity resulted in maximum heat indices of 109 degrees on Tuesday, August 22nd and 118 degrees on Wednesday, August 23rd at an automated weather observation station near Hokah.

Excessive Heat in WINONA, MINNESOTA
From 22-AUG-23 11:00:00 to 24-AUG-23 20:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: AWOS

The combination of anomalously high temperatures and humidity on Tuesday, August 22nd and Wednesday, August 23rd resulted in maximum heat indices of 100 to 118 degrees across Winona County. The maximum heat index reached 110 degrees on Tuesday in the City of Winona and 118 degrees on Wednesday in La Crescent at automated weather observation stations. The Minnesota Department of Highways reported heaved pavement on U.S. Interstate 90 near St. Charles on August 23rd. A nearby Minnesota Department of Transportation automated sensor measured a heat index of 108 degrees.

Excessive Heat in DODGE, MINNESOTA
From 22-AUG-23 11:00:00 to 24-AUG-23 20:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: AWOS

The combination of anomalously high temperatures and humidity on Tuesday, August 22nd and Wednesday, August 23rd resulted in maximum heat indices of 107 to 110 degrees in parts of Dodge County. The maximum heat index reached 110 degrees on Tuesday and 107 degrees on Wednesday at the automated weather observation station in Dodge Center.

Excessive Heat in MOWER, MINNESOTA
From 22-AUG-23 11:00:00 to 24-AUG-23 20:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: AWOS

The combination of anomalously high temperatures and humidity on Tuesday, August 22nd and Wednesday, August 23rd resulted in maximum heat indices of 109 to 115 degrees across Mower County. The maximum heat index reached 115 degrees on Tuesday in Austin and 111 degrees on Wednesday in Lyle at automated weather observation stations.

Excessive Heat in OLMSTED, MINNESOTA
From 22-AUG-23 11:00:00 to 24-AUG-23 20:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

The combination of anomalously high temperatures and humidity on Tuesday, August 22nd and Wednesday, August 23rd resulted in maximum heat indices of 105 to 118 degrees across Olmsted County. The maximum heat index reached 111 degrees on Tuesday in Stewartville and 118 degrees on Wednesday in Rochester at automated weather observation stations. The excessive heat resulted in the City of Rochester cancelling events for both days.

Excessive Heat in FILLMORE, MINNESOTA
From 22-AUG-23 11:00:00 to 24-AUG-23 20:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: AWOS

The combination of anomalously high temperatures and humidity on Tuesday, August 22nd and Wednesday, August 23rd resulted in maximum heat indices of 105 to 114 degrees across Fillmore County. The maximum heat index reached 110 degrees on Tuesday and 114 degrees on Wednesday at the automated weather observation station in Preston.