A week at Moonarie ... sounds like a good idea. It will most likely be clear giving pleasant climbing (in the sun) and freezin' nights. Overcast conditions would even out the day/night time temperatures. I find Moonarie generally cooler in winter than Arapiles: it's higher - Bottom Camp is about 500m above sea level, the Pines about 150m.
If you're there for a week you'll probably want to risk a climb or two in the shady Ramparts. You'd be comfortable in some light thermal gear and a beanie (and/or helmet!), but I'd schedule those climbs for the afternoon. The rock will freeze your fingers in the morning, after lunch it should be OK.