In reply to Ollie B:
Are you after rock or ice or the big stuff up high, or what? For rock, certainly, February is very tricky to predict - two years ago we had a spell of minus twenty down in the valley, and everything was under at least a foot of snow still. But the year before that, we could go cragging in the sunshine for all of January and February.
If it's a really shitty year for snow, you can climb some of the multipitches in the Aiguilles Rouges in February, but it would be a real gamble if you booked a flight now!