Gunter, you said unformal....maybe some nice bomber style windbreakers from places like Lands End, LL Bean, Orvis. Or a bomber style jacket from a golf course pro shop. If there are inside pockets you can also forgo the sporran.

Or just wear a vest, or one of those "fleece" warm up style jackets made out of old water bottles.



This is a light weight golf/bomber style from the Mirage Casino in Las Vegas



This is a replica War 2 tanker's jacket with Thinsulate added to keep the wind out.

Jean jackets look great with kilts too.




Ron