I once went on a desert field trip. My Botony prof and I laughed at the first time campers zippered inside tents as we shook out our sleeping bags. Sometime near midnight it SNOWED. We had to hop into his VW bug and sleep sitting up in our bags. In the morning two 6'+ men had to unzip and body slam the doors open. The various tents were all intact ( it was only a very cold, but 2' snowfall) but the occupants equally miserable. What is a true 4 season, or winter tent? Yes,They are usually more robust, which often merely camoflages design failures. The older tents of Rustrum, Kephart and Nessmuck were 'Balloon Cloth', a very lightwieght but tightly woven cotton. Better winter tents have an inner liner ( essentially 2 tents) which forms a warm air pocket, helps vent interior moisture and increase windproofing. You may also get a snow tunnel entrance ( think of a short tube) to trap heat and decrease dragging in wet snow somewhat. This is a true expedition,dead of winter, Robert W.Service winter snow tent. If wieght and overheating is a factor, there are some tricks. A tent fly is often offered to extend seasonal use in a 3 season version. A set of snow stakes, heavier or doubled up lines and a simple wisk broom will help. If your in real weather by all means build protective walls. That wisk broom is to brush yourself down before entering the tent.