The February 2021 North American cold wave was an extreme weather event that brought record low temperatures to a significant portion of Canada, the United States and parts of northern Mexico during the first half of February 2021. The cold was caused by a southern migration of the polar vortex, likely caused by a sudden stratospheric warming event that occurred the prior month. Temperatures fell as much as 25–50 °F (14-28 °C) below average as far south as the Gulf Coast. Severe winter storms also were associated with the bitter cold, which allowed for heavy snowfall and ice accumulations to places as far south as Houston, Texas, and contributing to one of the snowiest winters ever in some areas in the Deep South.