Karl Bohnak

Karl’s 5-day forecast

Summer got off to a quick start this year in Upper Michigan. An extended warm spell began on Friday, May 26 with a high of 80. The high temperature then exceeded 80 degrees for the next nine days, including two record highs of 91 degrees on May 31 and June 1. During this 10-day stretch, the mean temperature was 13 degrees above average at the National Weather Service (NWS) site near Negaunee.

An extended warm spell like we just experienced is rather unusual. Since records began at the site in the early 1960s, there have been only eight times with 10 or more consecutive days with high temperatures 80 or above. This streak that ended June 4 was the earliest such stretch of extended warmth. Three times, a string of 12 consecutive days of 80 degrees or above has occurred–from July 2 through 13 in 1981, from July 20 through 31 in 1999 and most recently, from June 28 through July 9, 2020.

As for consecutive 90-degree days, the one that ended May and began June was the second earliest on record. The earliest was May 29-30, 1986. That month was the driest on record at the NWS with only 0.06 inches of rain the entire month! Dry weather can help fuel a heat wave. That’s because the heat of the sun is not spent evaporating water out of the soil. One of our hottest summers on record occurred in 1988 in the midst of severe drought conditions all across the Midwest, including Upper Michigan.

The heat is gone for the time being, but the dryness has continued. A cold front will produce some shower activity today, and there’s a chance of more substantial rain across portions of the area early next week as a big, slow-moving upper-air low develops over the western Great Lakes.