Ok overnight I had the gauge right under the light about 1 foot away from the plant and the temp was 82 and humidity was 45... I just moved the gauge where it is pictured and temp went down to about 78 and humidity is now over 50 and rising.I like mine in the middle of the cab. For example if my cab is 48" ill mount it at 24", I like doing this because usually higher will be more humid and lower would be less humid. Peace and fire