Under what conditions does CPS close schools due to weather?

I’m a new teacher in Chicago from the Seattle area. Back in Seattle, schools would close if we got any more than about 2” of snow. Obviously it snows a lot more in Chicago, and Chicagoans are better equipped to go about their days safely with snow around, so it makes sense that CPS isn’t going to close down every time it snows a bit.

So, my question is when does CPS actually close due to weather? When it snows a foot? When it snows 2 feet? When it’s colder than 0 degrees?