Excessive Heat in Union, South Dakota

Excessive Heat August 15, 2025 – August 17, 2025 · Union, South Dakota

What the National Weather Service wrote

Dangerous heat index values peaked as high as 109 degrees at North Sioux City and 101 degrees 4 miles south of Beresford on August 16.

The wider storm

Heat and moisture pooled near and south of a nearly stationary frontal boundary across eastern South Dakota and southern Minnesota. Daily highs were in the mid 80s to lower 90s with dew point values in the upper 70s to lower 80s, yielding heat index values from 100 to 115 degrees.

Source: NOAA Storm Events Database, event 1291156. Narratives are written by the National Weather Service forecast office that issued the report.

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