Cool May finally gets some warmth

Dear Tom,
After a cool start to May, Chicago finally recorded its first 70 of the month last Friday. That seemed late to me. Is it?

Thanks,
Howard M. Elgin

Dear Howard,
It sure is. We had Chicago climatologist Frank Wachowski check the records and he found that the city typically records its first May 70 very early in the month, usually before May 5. This year it didn’t occur until May 12 when the mercury peaked at 73-degree and was the latest in nearly three decades since a 73-degree high on May 16, 1989. Wachowski noted that it marked just the 13th time since 1871 that it had occurred so late into the month and that nine of those occurrences were prior to 1943 when the city’s official observations were taken near the lake and subject to chilly lake breezes. The city’s latest date for the first May 70 was May 19 in 1871 and 1878.