Hey, you/your sister should submit a report of this squirrel spotting!
https://untamedscience.com/biodiversity/white-squirrel/
There's an effort to map where white squirrels are showing up in North America. We did some research after seeing one in our neighborhood a few years back - like this one, ours wasn't albino, which you can differentiate because squirrels with albinism have red eyes.
Edit: this lil guy is probably better off in the snow than otherwise, better camouflage! π