Gosh darn, it better not r...I'm not even going to say it.

Lorie, I would dress in layers. Perhaps a short sleeve T-shirt with a sweatshirt on top, and perhaps a light rain jacket. That way you can always remove layers. Lake Michigan is only in the high 40s for water temperature and if there is a breeze off the Lake, it is usually 10 degrees air temp cooler than the air itself. It will feel more like 15 degrees cooler. The Green Bay side of Door County will probably be a little warmer because it is sheltered with shallower water.

Hope that helps!