In reply to spidermonkey09:
Even with snow on the ground, slate should be climbable. It doesn't hold water and it dries quickly. cold under the hands but definitely worth it!
But yes, tremadog is definitely not just a plan B. It's probably one of my favourite places, even when conditions in the pass are perfect.
The moelwyns could be another option? Or else Jerry's roof on Cromlech boulders will be dry!