From Glossary of Meteorology
- As used in the U.S. National Weather Service, a rapid fall in temperature within 24 hours to temperatures requiring substantially increased protection to agriculture, industry, commerce, and social activities.
Therefore, the criterion for a cold wave is twofold: the rate of temperature fall, and the minimum to which it falls. The latter depends upon region and time of year.
- Popularly, a period of very cold weather.