Living in South Africa we are lucky to have such great weather to cycle in. But the downside is that when winter arrives so do the excuses. But it doesn't have to be that way, you will be surprised how comfortable cycling in the cold can be if you are dressed properly. Hence the saying, "There is no such thing as bad weather, just poor cycle clothing". Also you are better off mountain biking than riding on the road. Riding on the road you go faster and the wind chill is a big factor so you really need to have some serious clothing.
Mountain biking the speeds are slower and you are often climbing so there is almost no wind chill and the heat you generate keeps you warm. Get some decent warm gloves to keep your hands warm, that will keep you comfortable and able to operate shifters and brakes. Next you should keep your neck and head warm, a buff works really well if you pull it over the back of your head. It is light and not too hot and keeps the wind off. On your body you need to go with layers, ideally with everything moisture wicking so that your skin stays dry and warm. Start off with a short or long sleeve thermal top, then add a long sleeve cycling top and then on top of that a wind breaker vest or jacket. This should be more than enough and allow you to remove layers if it warms up later. On your legs a set of knee warmers will add that little bit extra leg warmth. Quality rather than quantity is the secret, get some good quality gear that is designed for being active in the cold.
