Dear Tom,
What is the longest time period Chicago has gone between reporting 70-degree temperatures?
— Greg K.
Dear Greg,
It can be a long stretch between Chicago’s last 70-degree day in the fall and the first one in spring. Typically the city experiences a break of 152 days from the end of October to the end of March. We had Chicago climatologist Frank Wachowski check the record books and he found that since 1871 the longest break between 70s was 203 days from Oct. 16, 1873, to May 6, 1874. However, prior to 1943, Chicago’s spring 70s were often delayed because the city’s official thermometer was located near Lake Michigan. The longest stretch since the thermometer was moved to an inland location has been 185 days, spanning the period from Oct. 21, 1943, to April 22, 1944.
