Definitions for "Cold wave"
Keywords:  unusual, weather, twenty, rapid, freeze
In the terminology of the United States Weather Bureau, an unusual fall in temperature, to or below the freezing point, exceeding 16° in twenty-four hours or 20° in thirty-six hours, independent of the diurnal range.
a wave of unusually cold weather
a rapid change in temperature that may cause the roads to freeze quickly, requiring extra precautions