Can you roughly determine the location of the sound? Is it up high toward the roof or down low, close to the fireplace?
It is 100% coming from the elbow area, but there's no residual sounds - just one bang, no rattling, no squeaking. I know it sounds weird, but the sound pattern is similar to hitting a nail with the hammer, just travels "down".
![[Hearth.com] Fireplace chimney making banging noise in wind gusts [Hearth.com] Fireplace chimney making banging noise in wind gusts](https://www.hearth.com/talk/data/attachments/277/277628-3933e4c444b698840cdc2d004447a325.jpg?hash=cH5iTbLQNX)