In a survival situation, getting overheated is one of the most dangerous thing that can happen. If you are all bundled up in extreme cold, while working you can sweat. Once you stop working, the moisture reduces the insulating properties of the clothes.

Another  thing in a survival situation is, NEVER eat snow. People get dehydrated and they eat snow thinking they are doing a good thing. It takes so much thermal energy to melt the snow, that it gives people hypothermia. You want to build a fire and melt the snow first, then drink it.