It’s been a frigid stretch of weather in the Chicago area, and if it feels unusual, your assumptions may be right.

Several inches of snow hit the Chicago area Sunday, causing hundreds of flight delays and cancellations and more closures at school districts across the area for Monday.

Chicago temperatures plunged well below zero Friday morning, with some places feeling as cold as -40 degrees. While an Extreme Cold Warning has expired, a Cold Weather Advisory is in effect until Saturday morning.