Dear Tom,

What is the latest date that we have ever experienced the coldest temperature of winter? —

Meg Sheehan, West Dundee

Dear Meg,

An interesting question as we endure Chicago’s coldest time of the year based on a normal high/low 31/18 from January 16-28. We had Chicago weather historian —Frank Wachowski— run the numbers. Checking back more than 150 years to the winter of 1870-71, the latest occurrence of the lowest temperature for any cold season occurred in March, and it happened only three times. The latest on record was a low of 2 above on March 6, 1960, with runners-up lows of minus 7 on March 4, 2002 and 4 below zero on March 2, 1913. It would be difficult to record the season’s lowest temp in March without snow cover, and all three dates had ample snow on the ground—5″ in 1913, 4″ in 1960, and 6″ in 2002.