In reply to Trevers:
Dunkeld is a couple of hours drive at most and is a sensible alternative.
Kingussie Crag near Newtonmore is often in the rainshadow of the mountains and whilst not nearly as good as adjacent Creag Dubh does have more routes at the lower grades.
Polldubh is the nearest and most obvious option but being situated in the wettest place in Scotland on the slopes of it's highest mountain, is unlikely to avoid any rain coming in (though it avoids the clag higher up).
Ardnamurchan is a good choice if the rain is only starting to linger over the mountains.
Cummingston is closer to 3 hours from Glen Coe, Logie Head further still, although the weather is almost always better.