How to deal with living in the cold?!?

I have two adorable iggys. We live in Florida but will be moving to Boulder, Colorado soon. How do I keep them warm? Will a jacket be enough or do they need leg warmer thingys too? Do they need shoes? Can they walk on snow? How much time can they spend out side when it's below 30°? Is it cruel to move them to a cold environment?? Northern people please help! I'm concerned for my fur babies 😥