Harry is already outside!

He is still bundled up in the accoutrements Bar provided: a massively puffy coat, and a pom-pom snowman hat.

Snow isn't necessarily anything new to him, but he hasn't had the chance since-- before he can remember, practically, since he was a very small child, to view it as anything other than a massive inconvenience.

So he's throwing snowballs at a tree, obviously.