subfreezing

adj

1. (not-comparable)Colder than the freezing point of water; below zero degrees Celsius or 32 degrees Fahrenheit.

   “The arctic cold front brought subfreezing temperatures, snow, freezing rain and treacherous driving conditions.”

   “A subfreezing December 1955 wind blows whistle steam past cab as J-5a 5439 with the Queen City yells for a Dayton (O.) crossing.”