A full ground stop was ordered at O’Hare International Airport due to snow and ice.

The ground stop, which requires all inbound planes to remain on the ground at their airport of origin, went into effect at 3:09 p.m. and was expected to last until 4:30 p.m. but could be extended as the snow storm continues to affect weather conditions, according to the FAA.

As of 5:15 p.m., 163 flights were canceled at O’Hare, and that number could continue to climb if weather conditions do not improve. Forty-two flights were canceled at Midway International Airport.

A winter weather advisory in Chicago was extended until 4 a.m. Wednesday, according to the Office of Emergency Management and Communications.

Officials said hazardous travel conditions were expected and an additional 1 to 3 inches of snow could accumulate overnight. The National Weather Service is also warning of potential flash-freeze conditions and black ice tonight.

Less than an inch of snow was measured at O’Hare International Airport, and 1.2 inches were measured at Midway International Airport as of 6 a.m. Tuesday. The snowfall was originally expected to be higher.

Snow is forecast to return to the area again later in the week, likely Wednesday night through Saturday. Chances decrease on Sunday, but it’s still possible the area could see flurries. Temperatures are likely to plummet by the beginning of next week, with forecasts predicting single-digit and negative temps by Sunday night.