Issued by the National Weather Service:

A wind chill warning is in effect from 5pm MST Tuesday until 10am MST Wed.

Dangerously cold wind chills expected. Expect wind chills of 30 to 40 below zero. The southwest wind of 10 to 20 mph with local areas gusting to 30 mph will also cause areas of blowing and drifting snow.

WHERE: Green Mountains and Rattlesnake Range and Natrona County lower elevations.

WHEN: From 5 pm this afternoon to 10 am MST Wednesday.

The dangerously cold wind chills could cause frostbite on exposed skin in as little as 10 minutes.  A wind chill warning means the combination of very cold air and the wind will create dangerously low wind chill values. Frostbite can occur quickly and even hypothermia or death if precautions are not taken.