Humidity is based on temperature. Although the thermistors used in these handhelds can have 10 second response time in still air, it's all lost in the thermal mass of the unit. You must let it normalize for 15-20 minutes.Originally posted by entropyknocks
I'm fortunate to have a friend two blocks away that has his weather station hooked up to wunderground.com.
To clarify, I don't mean a 10% difference, 40% vs 44%, I'd be fine with that, I mean a 10 point difference, 40% vs 50%. And worse, I put a new battery in the Extech and now it's a 13 point difference. If the Extech is accurate, then I could be looking at at mid to high 50's RH.
I have a Amprobe hygrometer and although the temperature is dead nuts compare to my calibrated Fluke 971, the %RH is off by 10%RH.