Excessive Heat — Plymouth, Iowa

2025-08-08 · Plymouth, Iowa

Event narrative

Dangerous heat index values peaked as high as 110 degrees 5 miles north of Sioux City, 107 degrees near Westfield, and 106 degrees 5 miles west of Brunsville.

Wider weather episode

High levels of moisture pooled along and ahead of an outflow boundary across eastern South Dakota and southwest Minnesota with dew point readings into the the upper 70s to lower 80s. With temperatures in the upper 80s to lower 90s, heat index values generally reached the 100 to 110 degree range during the mid afternoon to early evening.

Source: NOAA Storm Events Database, event_id 1291005. Narrative written by the NWS forecast office that issued the report.