Chicago's temperature hung out right around freezing from 11am Wednesday until 8pm last night. Then the cold front passed. This morning we woke up to -12°C with "warming" predicted to take that up to -9°C this afternoon. Then...it gets serious:
Below zero [Fahrenheit] wind chills Friday through Sunday drop to -20s Sunday morning.
We're looking at 10 days of overnight lows below -18°C and daily highs around -10°C. But then, this being Chicago, it will warm up like magic the week of the 22nd, and we'll forget once again how we get slammed like this every other February.