My argument is that it matters less in places that actually have an abundance of ducks (no where on the east coast). The outfitter I've hunted with in Arkansas has killed roughly the same # of ducks year in and year out for the past 15 years. The weather fluctuates hugely from year to year but their duck #s stay about the same. Yes of course, weather on any given day can make a big difference (I've been on slow hunts out there because of a lack of wind) but over the course of a season, it tends to even out regardless of whether it's a cold, hot, or normal winter.
Mexico is also the perfect case study. Usually the hunting conditions there are temps in the 60s and not a lot of wind...but yet they kill ducks by the truck load. This isn't a luxury we have on the east coast, but if you travel some place with enough ducks, you can have plenty of success without having ducky weather.