What fixes frozen fingers?
Fingerless mittens are one option, and while they don't cover your actual fingers, just warming your hands up helps a lot. I can still type and use a trackpad just fine with them.
If you don't need to use a touch-sensitive device with them, the really thin, lightweight gloves that are meant to be a layer underneath a heavier pair actually work great. I can work in them as normal and only give up a little bit of my normal typing speed; not enough to be a hindrance when doing software development since typing speed isn't the bottleneck anyway.