Unless you are in a Southern clime, when SHTF you are gonna need some cold weather gear. I live and work in North Dakota. I've loaded grain trucks outside in -25. -55 with the wind chill, I kid you not. This post may save your life, and I hope it does. I recommend an essential piece of lifesaving gear that won't take up much room in your ruck or bug-out bag. Under armor top and bottom rated 4.0. This is the pimp de-la-crème of all thermal undergarments. Here it is widely available. Where you are you may have to place a special order. By personal experience I can tell you this stuff bucks the wind like no other (WIND stands for We're In North Dakota) and you can work and operate comfortably in these without much bulk in the zeros. Added bonus - you don't have to get bulky carharrt bibs or overalls and you can stay in below-freezing temps for long periods of time. Take heed to this post, before it's too late. BTW: 30F to 40 F you actually feel hot wearing this gear during normal work and activity.