There's a few Calliphora sp. that manage to hang around throughout the winter; you'll generally only notice them around kangaroo carcases. I've no idea if these individuals live for more than a year, or if population's emergence times are spread right through early spring to late autumn. I know from collection work I've done, that the larger ones can reanimate after a few hours in a -20 freezer, so they'll probably have no trouble surviving a Canberra winter...