Rocky was always an indoor dog until about 1 year ago, when we moved house and I decided it was time for him to stay outside, as he is a Pitbull and I just cannot risk him in the house with DD.
He loves it outside, won't even come inside if I ask him to anymore, but it's getting cold, and I see him shivering, and the yard has no shelter. He does have a brick kennel, which he's a bit scared of and never used it.

How can I convince him to use the kennel?

What do you guys do to keep your dog warm in Winter?
(He has a cosy warm dog bed but it gets wet when it rains.)