I`ve got a friend that I grew up w/ that has a flow bench, they are very informative and interesting, would love to have one myself, but he takes care of me , so I don't really need one . I have seen the weather make a pretty big diff. on his too.
My second flowbench with manometers had a formula that you were supposed to use to convert your numbers over to account for weather changes. Heck on that I want to do a flow test and immediately see whether I helped or hurt a port.