Wind chills of -15F to -25F are expected in Casper until early Sunday morning, according to a wind chill advisory issued Saturday evening by the National Weather Service.

According to the advisory, the wind chills could cause frostbite on exposed skin in as little as 30 minutes. Hypothermia can also occur if precautions are not taken.

Buffalo and Kaycee are also included in the advisory, which covers northeast and southeast Johnson County, the Wind River Basin including Riverton and Shoshoni, and the lower elevations of Natrona County. The advisory is set to expire at 5 a.m. Sunday.

Slightly colder wind chills are expected for the Cody Foothills and the northern Big Horn Basin. Clark, Cody, Meeteetse, Basin, Greybull, Lovell, Powell and Shell are expected to see wind chills of -20F to -30F through early Sunday morning.

In addition, portions of south-central Montana should see wind chills of -25F to -40F through noon Sunday.