Excessive Heat in Pipestone, Minnesota

Daily afternoon and evening heat indices ranged from 100 to 105 degrees with a maximum heat index of 104 degrees at a Road Weather Information System site near Trosky on June 20 and 103 degrees at a RAWS site at Pipestone 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.