colder asphalt that you used to have in summer. cold nights cool it down so even when the sun is eventually above horizon, a lot of time with sunlight is needed to heat up the road surface.
tires are cold too, so make them warm with a gentle ride before some quicker style you may want. beware of paddles because they may have been frozen during the night.
also check the brake conditions.
make sure that you are dressed according to the weather conditions and also remember to have a waterproof rain protection with you. we always wish the best, but you must be prepared for any development. if you ride to a 