A tip for keeping warm by wearing the right clothes in the winter months, is to log every ride you do, marking down, what you wore as individual items, what the temperature was, max, avg and min and wind strenght. Record whether you was , hot, warm or cold, warm being the ideal. Even record if it was just your feet or hands cold and your body was warm. Basically you end up with a record sheet of a load of tick boxs, with dates down the left, and clothing items across the top along with the rest of the info to fill in.
When it comes to going for a ride, check what the min and max temperatures are predicted, consult your chart and look for a similar circumstance and what you wore and did it suffice, if not wear something warmer or cooler if its predicted warm or cold. If you do a lot of winter riding, you only have to do it for one year. Unless of course you buy lots of different jackets and jerseys etc. You will soon find that some items are better than others, even shirts branded coolmax can vary in warmth.
It removes all the guesswork which normally happens by just looking outside and hoping for the best you have got it right