I'd say there's a big difference between 41 and 45 and you're also greatly exaggerating the temperatures in Chicago if you include 105 as a typical high.

It's hit 105 a couple of times over the course of a hundred years. The hottest temperature since 2013 is 97. The average daily high in the hottest month is less than the bottom range of 85-105- it's 84.1 in July.

Hitting 45C is a big deal