Your internal temperature is sliding downward. Without treatment this slide leads to stupor, collapse, and death. Wool loses less, cotton, down, and synthetics lose more. Beware the wind. 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. Most hypothermia cases develop in air temperatures between 30 and 50 degrees F. Most outdoorsmen simply can't believe such temperatures can be dangerous. They fatally underestimate the danger of being wet at such temperatures. 50 degree F water is unbearably cold.