A brief, but intense heat wave brought the earliest 100-degree reading to Marquette on May 28, 1969. An upper-level ridge shot northeastward from the Southern Plains as low pressure formed in the Northern Plains. Strong, dry southwest winds ahead of the low brought a blast of heat into Upper Michigan. Temperatures had already soared into the 80s by 7:30 a.m. in Marquette. It reached 96 by noon and crept up from there, topping 100 by mid-afternoon.
The quick, intense warm-up wrought havoc on area roads. The heat caused deterioration of expansion joints; pressure built up and concrete literally ??exploded.?? Sections of U.S.-41 from Chocolay Township to Ishpeming needed emergency repairs. The worst eruptions occurred on concrete stretches that were 25 years or older.
While Marquette sweltered at the century mark, Calumet registered 95 degrees. A cooling breeze off Lake Michigan kept Escanaba a comfortable 81 degrees. It was still a sweltering 81 in Marquette at midnight. By early the next morning, a cool front slid through from the west, ending the extreme heat in time for the Memorial Day weekend.
The pattern we expect late this week into the weekend is roughly similar to the one back on that record-breaking day in 1969. An upper-level ridge will set up overhead on Saturday (Image 3). However, there is more of a northerly flow to our east which will hold strong high pressure just to east. This configuration will give us a more temperate south to southeasterly wind as opposed to the hot southwesterly winds that blew into the U.P. 45 years ago. Still, temperatures should approach or even exceed 80 degrees away from the influence of the chilly Great Lakes.