i wouldn't get a heavier jacket. i'd suggest a thin and light waterproof windproof jacket, unlined, with pit zips and reflective strips. when it gets colder than what you've got with a jersey and the century jacket, just put on the water&windproof jacket on top of it. or mix & match: short sleeved jersey, century jersey, and water&windproof jacket.

a heavier weight jacket is just the equivalent of another layer, so i wouldn't bother with that. on the other hand, a thin and light waterproof/windproof jacket is invaluable, imho.

sd