How can I prevent getting cold feet in the winter and summer?

Warm footwear. Wear heavy socks! if you smoke stop! can be a sign of poor circulation. Check with your doctor.
Circulation. If it is just in the winter, that is not unusual, but in the summer, it could signify some type of circulation problem. Some people are totally healthy, and still have similar symptoms. But I would see a Dr. just in case.