Excessive Heat in Cottonwood, Minnesota

Daily afternoon and evening heat indices ranged from 105 to 112 degrees with a maximum heat index of 112 degrees at a personal weather station near Westbrook on June 20, 111 degrees at a personal weather station near Storden on June 21, 107 degrees near Jeffers and 106 degrees near Mountain Lake at Road Weather Information System sites on June 21, and 106 degrees at the Automated Weather Observing System site near Windom on June 21.

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.