I have the kestrel 4000NV,and I get the best humidity reading by just setting it down and not holding it at all.I know they suggest holding it without interfering with the hole in the back,but I still get a higher reading no matter how I hold it,maybe it has something to do with my body heat in my hand?Whenever I set it down,the humidity reading drops pretty rapidly.Anyone else that has a Kestrel might want to try that also to see if it makes a difference,maybe it's just mine,who knows?You probably already know this but, you have to be careful how you hold a Kestrel when checking humidity. There is a hole on the back and if your hand is near it you can make it vary quite a bit.