Dear Chill,
I'm not kidding about dry. Without irrigation you may get zero hay harvests, depending on location.
That's completely correct. Rainfall total for the state is about 10 inches per year.
Platte County's chamber site: http://www.plattechamber.com/PlatteChamber/Demographics.aspx
lists farming as a business enterprise in the county. They also list these figures:
# Rainfall: 12.99
# Snowfall: 41.10
# Average growing season: 155 days
By way of contrast, Georgetown, Delaware shows rainfall of about 44.2 inches per year.
Another relevant eastern county, Laramie, shows about 15.4 inches rainfall total for the twelve months ending 31 August 2005.
http://www.wrds.uwyo.edu/images/wrds/wsc/monthsum/2005Aug/che_1yrp.gif
So, Chill's warning to be sure about your water rights is a good one. There are state and county regulations on drilling water wells to be aware of, I gather. It is not necessarily the case that any creek or river across your property is yours to dam up as you please. Water rights are very serious, sometimes quite elaborate, and because water is life, people are naturally quite intense about defending their actual and perceived water property rights.
By no means should you be discouraged from making the move, though. There are plenty of farms in Wyoming, lots and lots of which I see in eastern Wyoming on my travels. Farmers find water, so you can, too. Still, don't be mistaken about the water rights when you sign up for a land purchase. Know what you are getting in the bargain and you'll be glad you did.
Regards,
Jim
http://vertoro.com/