Are you looking for clematis species that will bloom during different times of the year so that you have year long flowers? Or are you just looking for an evergreen clematis? Clematis armandii is a hardy evergreen, but it blooms from march through april and a little in the summer in most areas, though I have heard of some people who's bloom late winter.
Clematis cirrhosa willl bloom in late fall and into winter some, and there are many varieties that you an choose from to bloom between early spring and late summer. I'm not sure about late winter though, and a lot depends on where you live.