When can we expect the last-freeze?

by: Mike Janssen, WGN-TV Weather Team, Tom Valle

Posted: Mar 3, 2024 / 02:03 AM CST

Updated: Mar 3, 2024 / 02:06 AM CST

The start of meteorological spring has many people wondering how soon we might be saying “goodbye” to temperatures that dip to at least 32º.  Despite the mild winter and a 7-day outlook that doesn’t include a freezing temperature in Chicago, it could be a while before the threat of a freeze ends.  

On average, the last freeze for much of the area happens between April 21-30.  That includes O’Hare Airport, Chicago’s official reporting station, where the last time the temperature falls to at least 32º, occurs on April 21 on average.  Last year, O’Hare’s final freeze of the season was on April 26, when the low reached 31º.  March 25th is the earliest Chicago has had its last spring freeze and that occurred in 1925. The record for the latest spring freeze in Chicago is May 25th, which happened in 1992.

The average last freeze occurs earlier for the heart of the Chicago metro.  The city’s heat island sees its last 32º or lower temperature between April 5-15 on average.  Just outside of the city’s center and into close proximity suburbs, the last normal freeze date falls between April 15-20.  A time that matches some far southern parts of northern Illinois.