In reply to Russell Brooks:
I did wonder if you meant rock rather than ice climbing. Since I suffer from mild Raynaud's I also need strategies for keeping my hands warm when climbing on rock, since it can strike on any cool day, irrespective of season. Here's a couple you might find useful:
If it's cool, I walk to the crag in ordinary gloves, with the handwarmers in the palm and I keep the gloves on when racking up. If I'm belaying first, I belay in the gloves, with the hand warmers moved to the back.
When climbing, I transfer the handwarmers to my trouser pockets, so whenever there's a one-hand/hands-off rest I can shove alternate/both hands in my pockets for a minute or two and warm them up. (If I let them get properly cold, it takes ages to get them warm again.) I've used this method when soloing, when working routes on a shunt, on sport and on trad. It's rare I'm on a route with no kind of rest at all and of course this method is fine on "warm-ups."
Post edited at 12:38