The National Weather Service in Des Moines says that "Freezing drizzle and light icing possible overnight into Friday morning, mainly west and north."

From the NWS Des Moines:

Patchy freezing drizzle may develop overnight with minor ice
accumulations possible, mainly north of Interstate 80.
Wintry precipitation is again expected late Saturday night and
Sunday, with light snow accumulations expected roughly north of
Highway 30. In addition, strong northwest winds of around 25 mph
with gusts in excess of 30 mph are forecast during the day on
Sunday. The combination of snow and blowing snow will reduce
visibility at times, mainly across northern Iowa, and could
impact holiday travel.