find a large barbeque grill cover that can slip over the trailer. Keep a spot for it shoveled out, and you'll be fine. !0 foot cable lock if needed to secure it to something on apartment. Bikes sometimes run better in winter if they don't make it inside to thaw overnight, the trailer will be perfectly happy staying outside.

One suggestion: create a warm seatcushion out of closed cell foam. keep THAT inside and bring out with the kid in the morning. it will make a comfort difference for the youth being strapped into a cold stroller.