Its going to be slightly annoying but what you are going to need is a full range of clothes to handle to handle temperature extremes. When your on your bike in the middle of the day then you won't feel that cold but if your feeling a little down after a hard days ride you are going to FREEZE on a cold night so you will need full thermal gear and a warm parka. You will most likely start the day's ride with some warm gear on and gradually remove some gear as the day progresses.
To be honest some of the gear you will need won't be available in any store anywhere near you so you will likely have to mail order it or get it on eBay. For riding I would suggest some SuperRoubaix long tights or bibnicks. Bibnicks have straps that go over your shoulders and are far more comfortable although they have one drawback in that they make it harder to go to the toilet. A thermal top and a windblocker top would be advised and of course gloves (regular and warm) and warm socks would be advised.
You will also need a large, warm parka to wear when your not riding and at night. After a hard days ride you will likely suffer from chills easily. Don't forget to take some gear for not so cold temperatures as well as it may get too warm for you on some days.
Anthony