Excessive Heat in Union, South Dakota

Excessive Heat June 29, 2026 · Union, South Dakota

What the National Weather Service wrote

Dangerous heat index readings reached afternoon peaks as high as 113 degrees near Dakota Dunes and 108 degrees in North Sioux City.

The wider storm

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.

Source: NOAA Storm Events Database, event 1351690. Narratives are written by the National Weather Service forecast office that issued the report.

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