2mm
is a bit thin for really cold water, but as someone said, it’s better than nothing. One thing about wetsuits is that they work well when wet. When dry in wind, they are surprisingly not all that wonderful unless you have some kind of wind-proof outer layer.
I’ve often wear a 3mm one while surf fishing, since wading out into 55F water and standing on shore after casting can get pretty miserable in most clothing. I learned quickly that if I don’t have a good wind-proof top on it gets really chilly.
Rick