What is the sound of teeth called that occurs in chilly weather: the sound that comes due to teeth crashing in each other in an extremely chilly winter.
The most common and idiomatic word to describe this situation is chattering.
chatter: click together repeatedly or uncontrollably
Chatter is the word you are looking for:
- If your teeth chatter, they knock together repeatedly because you are very cold or frightened:
- I could hardly talk, my teeth were chattering so much.