My hands are rainbows in cold weather what can I do?

Get warm! This may be describing a situation known as raynaud's phenomenon in which the arteries leading to the fingers and toes tighten up reflexively in response to cold, which make them hurt and even colder. Because of the rapid blood flow change, they often become white and then painful and red as blood flow returns. Keeping warm, massaging all help. See your doctor if severe, there are some meds too.
Hand color changes. There can be different causes for this such as raynauds or acrocyanosis. Raynauds is caused by blood vessel spasm and can be treated with medication. Acrocyanosis is a benign condition and is also helped by keeping the hands warm. You would want to see your doctor to further evaluate.