what's gotten into you?; what's come over you?
A set phrase expressing surprise at someone's uncharacteristic behavior or sudden change of heart. Often used rhetorically, not expecting a literal answer.
What's gotten into him? He suddenly started cleaning.
What's come over you? You're doing your homework without being told today.
Literally 'what kind of wind is blowing?', from the idea that a sudden change in wind direction brings unexpected weather, metaphorically applied to a person's sudden change in mood or behavior.