It's cold in Chicago right now: -7°C with a wind chill of -13°C and gradual cooling predicted towards a low of -16°C Wednesday night. This is only the second time in 30 years it's been so cold, so early.
Two things: first, though I don't have time to link to anything right now, it turns out this cold in Chicago is caused by abnormally warm temperatures in the North Pacific. So, yeah, aggregate global warming causes localized cold snaps.
Second, thanks to celestial mechanics, tonight's sunset will be later than last night's for every point on earth that has a sunset. (Inside the Arctic and Antarctic circles, there are no sunsets today.) Sunsets continue to get later everywhere until well past the March equinox, even though sunrises in the Northern Hemisphere will also get later until January 6th. (See the Chicago sunrise chart for details.)
So, despite this really unpleasant weather, there are definite signs it will get warmer soon. Relatively soon, anyway.