In my experience, they're hardy birds. They've been handling winters better than my ducks and chickens; only my geese have them beat.
BUT . . . I coop my guineas at night, and I keep them confined to the coop during very cold days. They can't move when it gets into the single digits - they'll...
Chinese geese always look so lean and graceful, especially when compared to the breeds I chose. I always imagine them as the ballet dancers of the goose world. How are their knobs doing in the cold?