you might want to try this is another spot (think there is one on travel) but at Christmas the Canary Islands or Egypt will be warm. Good luck! Will be pricey though if you have to travel during school holiday dates.
Went to the Canaries once and found it very odd sitting on the beach on Christmas Day, missed the turkey & trimmings, TV and even the weather. We found it was more Christmassy skiing in Austria and it could actually be quite warm. The family run accommodation was reasonable, very welcoming and they always made our son a birthday cake.