Growing up in Milwaukee I learned about cold weather early and got a refresher course every winter. These lessons served me well during two winters in Traverse City and as I write this from the Chicago suburbs. We have had milder weather recently but only a few days of sub zero wind chills are needed to get you thinking of a southern retirement. Cold temperatures are fatal to certain materials. About twenty years ago someone developed a real neat Klondike Derby sled for the Boy Scouts which could be cheaply and quickly built by the boys. Unfortunately, plastic pipe doesn’t like cold temperatures, something people discovered rather abruptly during an infamous -20 degree F outing I attended with my son. One minute those spiffy pipe sleds were gliding along, a bump on the rocks later they were a pile of shattered plastic. Metals can be evaluated for cold weather performance in the laboratory thanks to the efforts of engineers in several countries at the turn of the 19^th century. The impact methods they developed are now standardized as the Charpy V-notch test [ASTM E23, ISO 148-1or EN 10045-1]. Charpy ratings for various metals have proven to be instrumental in stopping the fracture of ship hulls in World War II and in making cold weather applications more reliable. We still have plenty to learn about designing for adverse conditions. NASA probably has more experience with this than any other agency but the average engineer would be wise to consider ambient temperature too. Your product may get air freighted and be exposed to extreme cold. I accidentally tested the flexibility of the foam in car seats during the winter of 1979; at -37F it doesn’t compress enough to allow the driver to fit under the steering wheel. Not that the engine started one I squeezed into the car and managed to get the key turned without it breaking off in the lock! Other projects required full scale testing of lubrication systems at -40F. We tired of replacing electric pump motors quickly and used very high viscosity fluids to simulate the cold flow of gear lubes. Our conclusions included not attempting to start pumps in below zero temperatures. Heaters were less expensive that replacing motors. Seals, and pumps.