Cold wave

A cold wave is when the temperature gets very cold for a period of time. It's kind of like when it's really cold outside and you have to get your winter coat and hat out. Cold waves happen in the winter and can last for several days. During a cold wave, the temperature usually stays below freezing (32 degrees Fahrenheit or 0 degrees Celsius) and can sometimes even go down to -20 degrees Fahrenheit (-29 Celsius). The cold air that causes a cold wave comes from the North Pole. People living in parts of the US and Canada can experience cold waves when the North Pole air moves south and becomes more common in the lower parts of North America.