I wouldn't wear a jacket for those temps.

I wear a long-sleeve wool shirt over a baselayer. Something like one of these.

http://www.ibexwear.com/shop/product...s-zepher-sport
http://www.icebreaker.com/site/icebr...lalom_zip.html

There's cheaper ways to do the same thing, but I'm a wool addict now. It helps that I wear a large so I can get the Icebreaker sales samples that hit the internet twice a year.