I know once it gets really cold propane gels like diesel and won't flow, some people that I camp by hunting run heat trace around their 100 pound bottles to keep the tank warm, last year when it was 22 below they had issues I did not but was using the bottles on the side of the camper that get a little heat from the wall they are against and their bottle was outside. There are a lot of cool things out there to keep the bottle warm, weigh the bottles to know how much is left and all.