A winter storm that could bring four to seven inches of snow is heading toward Northern Illinois. The National Weather Service has issued a winter storm watch beginning Friday morning at 9 a.m. and ending at midnight. This is the second winter storm watch issued in eight days; the typical weather of the season has officially arrived.

As of 10:30 a.m. Friday, the Chicago Department of Aviation reports 300 inbound and outbound flights have been canceled at O’Hare International Airport. At Midway International Airport, Southwest Airlines has cancelled all flights scheduled between 2 p.m and 5 p.m.

Friday’s rush hour is also expected to get messy as snow may fall at a rate of one inch or more per hour starting around noon.

Meteorologist Matt Friedlein with the National Weather Service said temperatures will top out in the upper teens, maybe 20 degrees.

“That is cold enough that it’ll make the cleaning crews for the roads have a little extra challenge there as salt and other chemicals may not work as effectively with temperatures in the teens,” Friedlein said.

Snow should taper out after Friday evening and the lake effect will likely cause more snow on the Illinois side of Lake Michigan.

On Sunday temperatures will warm and the Chicago metro area could get some rain in the evening.

Friedlein said this fast-moving storm originated in Western Canada, and is the same system that dumped snow on Seattle this week.