Off grid factoid....

I've lost count... how many am I up to?
Tonights lesson is on propane. When it's colder than 40° all day you don't have enough vapor to run all the stuff you need to make life comfortable. Found that out the hard way today. Generator was running fine, but after awhile the house started to get a bit cold. A quick check of the pilots prove the problem, the demand from the generator out paced the bottles ability to produce vapor. Resulting in a drop of pressure beyond the generator. So after shutting down the generator, a relight of the essential pilots and we should be good. Question is, how cold before there isn't enough pressure to run the essentials?
I guess there is only one way to find out.