What is the yearlong variation in temperatures this year?

Dear Tom,
I know that the last couple of months have been cooler than normal, but with the heat excesses from the other nine months, what is the yearlong variation?
— Bob Truby, Downers Grove
Dear Bob,
We sent your request to Chicago climatologist Frank Wachowski, who keeps a running tab on the city’s annual temperature surpluses or deficits. Wachowski reported that despite the city’s chilly fall, 2018 will still finish above normal. Through Dec. 15, the city’s official temperature departure was plus 348 degrees (1.00 degree above normal). He noted that the year’s peak temperature surplus was 550 degrees on Oct. 12 (1.93 degrees above normal), so the city’s recent chilly spell has reduced the annual temperature surplus by nearly 1 degree.

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