It’s not the gasoline. It’s the vapor—remember all these posters talking about evaporation? That’s vapor. And we in Phoenix have seen enough fires from such a scenario. Don’t laugh until you get all of the facts.
In my one ton box van I actually ended up with almost 5 gallons of gasoline on the rubber floor several years ago, soaked in, and the rest in vapor (it is fairly air tight although I always leave a vent open a little bit now). It was really a miracle no explosion occurred when I opened it up — lots of metal-to-metal contact going on. Glad my guardian angel didn’t take that day off. Don’t ever leave the generator’s fuel petcock in the on position.
Gasoline vapor igniting has nothing to do with heat. Gas vapor has a flash point as low as -50 F. And the autoignition temperature of gasoline vapor is even higher than liquid gasoline (around 530 F). At any rate, that’s why you use a cap on your gas can or gas tank. So the vapor can’t be ignited by a random spark, whether it is the middle of winter in Alaska or summer in Arizona.