In water less than 50 degrees you should wear a wet suit or dry suit to protect more of the body. When clothes get wet, they lose about ninety percent of their insulating value. Wool loses less as does many of the new synthetics. Cotton and wet down are worthless. A slight breeze carries heat away from bare skin much faster than still air.
Wind drives cold air under and through clothing.
Wind refrigerates wet clothes by evaporating moisture from the surface. Wind multiplies the problems of staying dry. Direct sunlight on the skin helps in the warming process. Terminate exposure if you can not stay dry and warm under existing weather conditions, using the clothes you have with you, do whatever is necessary to be less exposed. People who live in poorly heated homes risk getting accidental hypothermia when the weather is cold.