I’m hearing the temperatures may reach the 90s in upcoming days. How common are 90-degree days in May?
Not very. May, with a long-term average of two 90-degree days marks the very start of Chicago’s hot weather season. May 1977 leads all other Mays with 10 days in the 90s, and reigns as the city’s all-time warmest May. That year the heat arrived after a very cool period from May 8-10 in which the city recorded three frosty lows in the lower 30s. After three warm days in the middle and upper 80s, the mercury soared to a summery 91 degrees on May 16, the first of a string of nine 90-degree days. Three more days in the 80s followed before the month’s final hot day, with a high of 93 was recorded on May 28. The city’s last May 90s occurred three years ago in 2018 when four consecutive were logged from May 25-28.