Product review (1 stars): Outdoor humidity sensor doesn't work.
I read the reviews that stated that the outdoor sensor wasn't accurate.  It was still rated over 4 stars in general, so I decided to get this anyway.  The outdoor sensor really isn't that accurate.  I set it up inside with the indoor and outdoor sensors right beside each other.  After a while, they did have the same reading (within the accuracy of the sensors).

So, I moved the outside sensor outside.  In a shaded, but open to air movement, area.  We live in Utah, so the humidity was what I was mainly interested in.  Not long after being moved outside, it was reading the humidity at 1%--which was obviously wrong.  I gave it a full 2 days to get acclimated to the environment.  During that 2 days, it read everything from 1% to 99% and never anything close to the weather station one street over on Wunderground.

I thought, I just got a bum one.  I returned it a got a replacement.  The second one did exactly the same thing.  So, it's going back.

I guess I'm just going to have to use Wunderground instead.