Sleeptalker looks to have made some good points that should help - sad that the dog cannot be inside - but as you have said there are reasons for this - and I would suspect the dog is far better off now then it was (thanks to you). Also as wel as making sure the kennel has adequate covering on the top also rais if off the gound (on bricks if need be) by a few inches - also could you buy a dog fleece/coat for the dog.
regrds
Sue