Heat and humidity developed across the area on Saturday September 2nd and continued through Monday, September 4th. Temperatures on Saturday exceeded 100 degrees across central and north central South Dakota, while northeast South Dakota experienced heat index values above 100 degrees. A peak heat index of 114 degrees was observed on a personal weather station 3 miles southwest of Onaka, while Pierre regional airport observed a high temperature of 103 degrees. A daily record of 101 degrees was set in Mobridge as well.
On Sunday, 100 degree heat and heat index values over 100 degrees were more broadly spread across central, north central and northeast South Dakota. The state mesonet station in Oacoma recorded a high temperature of 104 degrees, and the Automated Weather Observing System (AWOS) 3 miles east of Milbank recorded a maximum heat index of 107 degrees. Watertown set a new daily record of 101 degrees, while the record of 99 degrees was tied in Mobridge.
Again on Monday, a broad expanse of 100 plus degree heat and heat index values were observed from central to northeast South Dakota, with the highest heat index value of 110 degrees observed at the South Dakota Department of Transportation sensor in Mellette, while the state mesonet station 16 miles south southeast of Fort Pierre recorded a high of 103 degrees.
While this 3-day period experienced both abnormal heat and humidity, for the most part temperatures and heat index values dropped below 75 degrees for at least a few hours in the morning.

Excessive Heat in SPINK, SOUTH DAKOTA
From 02-SEP-23 13:00:00 to 04-SEP-23 18:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Excessive Heat in HAMLIN, SOUTH DAKOTA
From 02-SEP-23 13:00:00 to 03-SEP-23 18:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Excessive Heat in HYDE, SOUTH DAKOTA
From 02-SEP-23 13:00:00 to 03-SEP-23 18:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Excessive Heat in BUFFALO, SOUTH DAKOTA
From 02-SEP-23 13:00:00 to 03-SEP-23 18:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Excessive Heat in HUGHES, SOUTH DAKOTA
From 02-SEP-23 13:00:00 to 03-SEP-23 18:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Excessive Heat in JONES, SOUTH DAKOTA
From 02-SEP-23 13:00:00 to 03-SEP-23 18:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Excessive Heat in LYMAN, SOUTH DAKOTA
From 02-SEP-23 13:00:00 to 03-SEP-23 18:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Excessive Heat in DEUEL, SOUTH DAKOTA
From 03-SEP-23 12:00:00 to 03-SEP-23 18:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Excessive Heat in GRANT, SOUTH DAKOTA
From 03-SEP-23 12:00:00 to 03-SEP-23 18:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Excessive Heat in HAND, SOUTH DAKOTA
From 02-SEP-23 13:00:00 to 03-SEP-23 18:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Excessive Heat in EDMUNDS, SOUTH DAKOTA
From 02-SEP-23 13:00:00 to 02-SEP-23 19:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Excessive Heat in CLARK, SOUTH DAKOTA
From 02-SEP-23 13:00:00 to 02-SEP-23 19:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Excessive Heat in SULLY, SOUTH DAKOTA
From 02-SEP-23 13:00:00 to 02-SEP-23 19:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Excessive Heat in STANLEY, SOUTH DAKOTA
From 02-SEP-23 13:00:00 to 03-SEP-23 18:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Excessive Heat in BROWN, SOUTH DAKOTA
From 02-SEP-23 13:00:00 to 04-SEP-23 18:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Excessive Heat in FAULK, SOUTH DAKOTA
From 02-SEP-23 13:00:00 to 04-SEP-23 18:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet