We've got a classic weather event rolling through Chicago right now:
What makes it atypical is the low pressure over northeast Minnesota (980 mB) and the tight pressure gradient around it. So while the temperature at IDTWHQ has gone up 7.2°C (13°F) in five hours—2°C in the last hour alone—we've also got a bit of wind. O'Hare reports southwest winds at 16 kts with peak one-minute winds of 39 kts, which qualifies as a fresh gale.
But you see that blue line curving through Minnesota, South Dakota, and Wyoming? That cold front will slide through Chicago overnight, bringing us below freezing for a couple of days.
For what it's worth, the normal temperature range for March 1st is -3.1°C to 4.9°C. We should get that entire range between 8pm and 3am tonight.
So this isn't really that unusual for Chicago. March has the most variable weather of any month here. That's why we dress in layers.