I was going on a cold weather quail hunt several years ago and have used Green Dot as my primary powder for 12 gauge for decades. I'd never had a problem with them before, but it doesn't often get really cold where I live and I had read somewhere that GD could have issues with cold weather.
So I called Alliant and asked them. The guy I talked to said I should use Unique instead of GD in cold conditions. I did, and it worked fine. Unique may not be suitable for your needs, but at least I thought I could tell you that Alliant confirmed that GD has issues with cold weather. Good luck finding what you need.
