Cold winds made the temperature low to 10°C below zero?
ᴀ.ɴᴇɢᴀᴛɪᴠᴇ 10°C
When dealing with a weather forecast in the U.S., subzero means below 0°F. It's a convenient way for the weatherman to say, "It's going to be dangerously cold!" In a similar way, on a warmer day, you might hear a forecaster saying things like, "with lows in the teens" or "with highs in the upper 20s.
