Chicago has microclimates. If you get within about 2 km of Lake Michigan on a hot day, you can feel it even if the wind is calm. Add a lake breeze and the cool zone can extend 10–15 km easily.
It turns out, Inner Drive Technology World Headquarters and its Netatmo weather station sit just over 2 km from the lake (it's 2,170 meters to Foster Beach). O'Hare, Chicago's official weather station, is 21.5 km from the lakefront (in Winnetka, because Geometry!).
I've seen days with stiff east winds (usually convective lake breezes) where O'Hare was 15°C warmer than my own weather station. But I haven't had any visibility into how much colder it was at the lakefront than here.
Fortunately, one of my friends just got their own Netatmo weather station, and they live only 580 meters from the lake.
After tweaking some adapter code, Weather Now now has their weather station data to go along with mine! So we'll both be able to see how much the lake influences the weather even over such short distances. At the moment, their station shows 10.4°C and mine shows 11.2°C, while O'Hare is reporting 19°C. Not surprisingly, the winds at O'Hare are out of the east—but only 10 km/h, a gentle breeze.
I'm sure I'll have other comparative reports throughout the summer, especially when I take Cassie to the dog beach.