I recommend a LONG coat with a hood. It's not just the insulative value that's important, it's the amount of the body covered.
This works for me in Maine (and of course is from LL Bean!).
I should add that I also have a pair of LL Bean Ski Pants (not insulated, just thick and stretchy) that I put over pants and sometimes long johns to walk the dog. Layering the bottom helps with the whole body.
Plus I layer mittens and gloves.
Now, back to enjoying August in Maine . . . the fleeting summer is too short for the computer.
