Collocations for frosty - adj.

be, look | become, get, turn
when the weather turns frosty

remain, stay

very

cold and frosty
The day dawned cold and frosty.

be, look, seem | become, turn
He cool green eyes became positively frosty.

remain

decidedly, distinctly, positively, very
The atmosphere in the room was decidedly frosty.

pretty