Go to
www.wunderground/history to get average high and lows temperatures and rain and snowfall averages for any particular week or month. Then type in the name of the nearest decent size town. I use that when I am hunting a new state. Of course, the weather the last few years has been weird all over.
As Jen said, weather can vary a lot so take layers, mainly merino wool. Include a rain layer. Check out the Eastman home page to see Guy's recommendations on layering.
As for boots, I love my Danner Pronghorns. You can get them without insulation. Make sure your boots have good soles, waterproofing and very little flex. Check that out by trying to push both ends together to make a V.
Good luck. I am trying to work out a bear hunt for September, too.