In reply to CJD: Gosh. The pressure.
As has been said, be prepared for all sorts. In summer you should be fine in something lighter but if you're going to be on a shady south face in a southerly it can still be pretty chilly. I tend to use some Salomon leathers from about November onwards but carry a couple of plastic bags that can go inside boots, over socks to help keep my feet warm if the boots get soaked. I'd say it is comparable to the European Alps in summer if you discount the really high peaks like Mt Blanc.
In winter you might suffer a bit more. Two acquaintances both came off the South Face of Douglas in September this year with frostbite (serious enough for hyperbaric chambers but, as far as I know, no lost bits,) after climbing it in leathers. Personally I use ski-touring boots for winter routes but would want plastics otherwise.
It depends a bit on what you're doing and how well you get on in the cold but if you're planning any winter Alpine trips then you might need to think about the beefier option. Remember that you'll almost certainly need snow-shoes if you're not skiing, too.
Feel free to drop me an email if there's anything else.
