Everywhere will be open, xmas is one of the busiest times in the canaries. The weather can be mixed, it can rain, it can be sunny. Usually more sunny than rainy. Whatever it is, it will be far better than the weather in the UK at the same time so don't worry too much about it.
been the last 2 christmas and we have done well with the weather a miture of clouds and sunshine but mostly sunny and was in the pool everyday but it was heated all restaurants open found it very expensive last christmas because of the euro hoping togoagain this christmas