It's a good thing the humidity isn't as critical as the temp. +/- 5% each way either during hatch or lockdown at least isn't going to kill 'em but +/- 5F one way or the other would.When I 'salt test' calibrate my Accurite Hygrometers, I will calibrate them 3 times and take the average for determining the true %Rh....very rarely will any hygrometer read exactly the same % every time it's calibrated....I only have one that is that reliable, out of 12.