I noticed that we were stuck on a normal high of 31 degrees for quite a while. What normal high temperature has the longest run during any one period of the year?
-- Jim Birkett, Park Ridge
You’ve hit the nail on the head: The 28-day period from Jan. 2 to 29 when Chicago’s normal high temperature is stuck on 31 is by far the city’s longest. Now the normal high temperature has begun a slow but steady climb to an eventual normal peak of 85 during the second week of July. It then will slowly decline to 31 degrees by next Jan. 2.
The current normal temperatures were derived from a smoothed average of temperatures recorded at O’Hare International Airport during a 30-year period from 1981-2010. The city’s climatological norms will be recalculated in 2021.