AWIB
Aerodrome Weather Information Broadcast
This is because it transmits Weather Information at an Aerodrome by Broadcast.
Take it from me, I build the bloody things.
The coldest part of the night is subject to perception. True lowest temps can be part way through the night and then come up because of, strangely, weather patterns. You would think the coldest part should be just about sunup but it can be an illusion of expectations in your own mind.