Gradual cooling gives plants time to adjust internally and harden off, thus withstanding cold. The absolute minimum temperatures affect plants, not wind chills. Wind chill is a human measure and means nothing to plant material. Plants are rated as to their absolute winter temperature tolerances based on plant hardiness zones. Hardiness zones classify trees, shrubs, and flowers by the lowest temperature they will survive.
Hardiness zones range from eleven to one.
Zone eleven is southern Florida and Hawaii while zone one is the tundra of Alaska. Kansas is divided into two zones. Zone five is the upper part of the state including the Kansas City area. The southern half of the state is in zone six. Plant materials hardy in zone five will survive minimum winter lows of minus ten to minus twenty while zone six tolerates temperature to minus ten.