Dear Tom,
Has Chicago ever recorded a temperature of 90 degrees or higher in the fall after a
sub-40 degree low?
Brandon D. Lade
Dear Brandon,
It hasn’t happened often, but we can find at least three such occurrences including one
just last year. On Sept. 15, 2007, Chicago set a record low of 39 degrees. Just nine days
later, on Sept. 24, warmth returned, and the city officially logged a high of 90. Similar
occurrences were noted in 1956 when after a 38-degree low on Sept. 20, the mercury
soared to 92 degrees just two days later on Sept. 22; and in 1951 when a 38 on Sept. 28
was followed by a 90-degree high on Oct. 4. Though 90s after 30s are rather
uncommon in Chicago, early season chills are often followed by warm-ups in the 70s
and 80s as northerly winds in the buckled jet stream that brought the chill move east,
putting Chicago in a warm southerly return flow.
