Gloves,hand warmers,chemical heat packs,stay out of the cold.
I have been searching for an answer myself. I came upon something called Raynaud Phenomenon. It has to do with circulation. The hands/feet turn blue/purple then white/red. And usually when the hands/feet are cold. I don't believe it is serious. I just rub my hands together a lot to get the blood flowing. If you are a smoker check out Buerger disease. Again it's a circulation problem, the arteries become constricted if you are a smoker. Not good. I'm concerned enough to check with my doctor as I've been a smoker for 45 years and it's only recently that the cold purple hands have presented. Hope this helps in any way. Take care.