Checking humity in the windrow

  I have a few questions about this,Hay Wilson talked about it and he does it,I bought a meter for reading humity at the hardware store and put it in the windrow just above the ground and made sure it was covered from the sun had to put a stick up to find where I put it,I think he said any reading under 65 the hay is dry enough to bale and have put in windrows that are very green and it might get to about 75 and always let it set there for about 20 minutes or so,am I doing this right and am I using the correct meter just seems like it wasnt working very accurate,can somebody educate me on this ? This is on bermuda grass in east texas where we have high humity. Thanks

Checking humity in the windrow