Excessive Heat in Moody, South Dakota

Daily afternoon and evening heat indices ranged from 100 to 106 degrees with a maximum heat index of 106 degrees at the Automated Weather Observing System site at Flandreau on June 21, 106 degrees at the Road Weather Information System site 13 miles west of Ward on June 20, and 105 degrees at the South Dakota Mesonet site near Flandreau on June 20.

The upper-level pattern experienced amplification of an eastern U.S. ridge and western U.S. trough, which locked a low-level frontal boundary in place from western Nebraska through central South Dakota into the Great Lakes. This allowed for heat to spread northward as very high dew point readings pooled across the area with the recent wet conditions. This multi-day dangerous heat event featured daytime heat index readings from 100 to 120 degrees, with nighttime low temperatures remaining from the mid 70s to lower 80s.