In reply to Phi:
Phi, sorry for slow reply.
As you say in Feb it can be a bit risky as Feb, March and April are the least stable months for rainfall.
However, it can be brilliant as well with cold clear days and great temps. Basically at that point the general situation is that all the wall climbs remain dry while the tufas are generally wet. And therefore certain crags are better than others so it also depends what grade you are climbing and what you are looking to do.
When the sun's out it's still hot and you can climb in a T shirt...
In Leon, on the plata, it's generally more stable weather at that point and there are more crags which remain very climbable - the only problem is the cold at night as it's nearly at 1000m+...Leon is where the Asturian climbers tend to go in winter.
To be honest though I'd say the back end of the year is a better bet than after Xmas - generally over the last 5 or 6 years it's been very good up until mid-Jan. Obviously depends when you're free...