* WHAT...Very cold wind chills as low as 15 below zero expected.

* WHERE...In Illinois, Saint Clair IL County. In Missouri, Saint Louis City MO and Saint Louis MO Counties.

* WHEN...From midnight tonight to noon CST Tuesday.

* IMPACTS...The dangerously cold wind chills as low as 15 below zero could result in hypothermia or frostbite if precautions are not taken.