I wanted to add..
With my cool-idor setup, I use a wireless hygrometer (generic weather meter) I bought from Fryes. It is capable of reading 3 different remote stations from the base station. That way I don't have to open up my cooler to check the temp/RH and I can bring up 2 other remote stations when I need to. They are spot on and only around $20.
Oh additionally, the remote stations and the base station displays the temp/RH of its surroundings. Its like getting 2 hygrometers in the package.
Here's the link!
wireless hygrometer