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FOX 32 – 10 day High Temperature graph starting Tuesday, July 22
CHICAGO – An Extreme Heat Watch is in effect Wednesday through Thursday.
As high temps reach the upper 90s for nearly all of Illinois and heat index values are expected to rise between 105° and 115°, let’s take a deep dive into how the summer of 2025 is stacking up against previous years in recorded history.
Courtesy of CHICAGO O’HARE INTL AP (1959 – July 21, 2025)
At O’Hare International Airport, the weather station has kept a data log of weather variables from temperature to barometric pressure since 1959. Thus, for fun, we have access to the number of days that are equal to or exceed 90° in Chicago per year.
Stats at a glance
- Average number of 90+ degree days per year : 17 days
- Year with most 90+ degree days : 1988 (47 days)
- Year with the least 90+ degree days : 1967, 2004, and 2014 (3 days)
- 90+ degree days so far in 2025 : 18 days
Looking forward 
Courtesy of CHICAGO O’HARE INTL AP (1959 – July 21, 2025)
As of Monday, the only years that outpace the total number of 90+ degree days that we’ve seen so far in 2025 are 1983, 1987, 1988 and 2012. It is important to note that the pace is statistics-based, which does not factor in meteorological observations that will sway the actual number by the end of the year. While the past is not a predictor of what is going to occur in the future, it does tell us that if this pace continues, Chicago could have about 16 more days of 90+ degree weather.
According to the Climate Prediction Center’s Seasonal Temperature Outlook, Chicago is forecast to have a 40-50% probability of seeing temperatures above the climatological average. It is not out of the question that summer 2025 may rank high on the all-time list in recorded history at O’Hare.
Courtesy of NOAA’s Climate Prediction Center as of July 17, 2025