I can stay with a top jacket at 15 degrees easily....
I am loving the Betz Full John. Keeps me warm and comfortable all day in the water. Dries fast. So light at times I almost forget I’m carrying it.
Soft but yet so supple. Touches my body in all the right places and keeps me warm until I’m too tired to go anymore. Dries really fast and is ready for round two before I am. Highly recommend for those warm San Diego days and definitely worth the money.