DES MOINES (AP) - Iowa public safety officials were urging motorists not to travel in north-central and northern Iowa on Saturday as the state braced for more snow, high winds and bitter temperatures.

Courtney Greene, a spokeswoman for the Iowa Department of Public Safety, said travel was not recommended on Interstate 35 from central Iowa north to the Minnesota border.

"We really do not want people (to travel)," she said. "If they do not have to travel, they should just stay put."

The Iowa State Patrol issued a news release Saturday afternoon warning that state highways and rural roadways are covered with black ice and are "extremely hazardous."

Col. Patrick Hoye with the patrol said black ice often can't be seen, and he urged caution especially on highways, bridges and overpasses where black ice forms more easily.

"Many drivers don't realize the dangers of black ice until it's too late," he said in a statement. "Black ice is one of the most dangerous conditions drivers can encounter.

He advised Iowans to stay off the roads.

Greene said a double fatal accident on Saturday afternoon near Mitchellville in central Iowa was being blamed on the winter road conditions. No other details on the accident were immediately available.

Iowans were slammed with sleet, ice and snow on Thursday into Friday, but Frank Boksa, a meteorologist with the National Weather Service in Johnston, said Saturday that the most dangerous blizzard-like conditions were still on their way.

He said high winds reaching 35 miles per hour and bitter cold temperatures with wind chills dipping to 25 below zero were expected to make their way across Iowa later Saturday into Sunday.

"The worst is going to come tomorrow when we keep the wind and we introduce much colder air," Boksa said, adding that western Iowa was already experiencing some of the high winds on Saturday.

While snowfall was expected to be less than 4 inches, he said the high winds posed dangers for travelers for several reasons, including blowing around snow already on the ground and reducing visibility on ice-covered roads.

He expected to winds to diminish by Sunday evening.