The record high and low for July 28 are just one year apart. How often does that happen?

Dear Tom,
The record high and low for July 28 are just one year apart. How often does that happen?
—Thomas Leeth, Hammond
Dear Thomas,
The short answer from Chicago climatologist Frank Wachowski is not very. He checked the record books and found just six such occurrences. The one you cited, July 28, had a record high of 100 in 1983 followed by a record low of 51 in 1984. The city’s most famous example of this are the Christmas Day extremes of a balmy 64 in 1982 and a frigid minus 17 in 1983, but with the same weather regimes in place a few days earlier, Dec. 23 was 62 in 1982 and 21 below zero in 1983. Other year-apart examples include April 21, with 88 in 1985 and 27 in 1986; May 11, with an 89-degree high in 1982 that followed a low of 33 in 1981; and Oct. 21, with a record low of 26 logged in 1952 followed by an 87-degree high in 1953.
Chicago climatologist Frank Wachowski checked the record books and found just six such occurrences.