From June 15 to September 7, 1901 Prairie du Chien, Wisconsin had 36 days over 95 degrees, peaking at 110 degrees on July 22.
22 Jul 1901, 1 – The Oshkosh Northwestern at Newspapers.com
New York also had one of their worst heatwaves that summer.
Another remarkable heatwave occurred in 1895. From April 18 to September 25, 1895 Prairie du Chien had at least 120 days over 80F, including 90 degrees on April 22.