Greet cold weather (4)
I believe the answer is:
hail
I believe this clue is a triple definition!
'greet' is the first definition.
(I know this)
'cold' is the second definition.
(I've seen this before)
'weather' is the third definition.
(I know that hail is a type of downfall)
(Other definitions for hail that I've seen before include "An ancient Roman hello" , "An old Roman salute as to Caesar" , "Old Roman salute, or frozen pellets" , "Frozen rain or Roman greeting" , "cold weather" .)