Cold & Temperature
Cold weather terminology — from wind chill to flash freezes. The terms that explain why it feels colder than the thermometer says.
Deep Freeze
An extended period of unusually cold temperatures, typically below 0°F, that threatens infrastructure such as plumbing, vehicles, and the power grid. Deep freezes trigger primal anxiety because everyday systems become fragile.
Flash Freeze
A rapid, dramatic temperature drop that turns wet roads and surfaces into solid ice within minutes. Flash freezes typically follow rain showers as a strong cold front moves through.
Polar Vortex
A large mass of cold air normally circling the Arctic in the upper atmosphere. When the vortex weakens, frigid Arctic air spills southward into North America and Europe, producing dangerous deep freezes.
Subzero
Air or wind chill temperatures below 0°F. Subzero conditions can cause frostbite within minutes of exposure to bare skin and are the threshold at which schools commonly close for cold alone.
Wind Chill
The apparent temperature your skin perceives when wind speed strips heat from your body. Wind chill is what makes a 20°F day with strong wind feel like -5°F, and it is the primary measure used in cold-weather school closure decisions.