That's a bull snake, also known as a gopher snake, (Pituophis catenifer) and yes, they do like to hiss a lot and bluff that they're mean and tough.  They can be from 36 to 80 inches long and pose no danger to humans or pets. They use constriction and suffocation rather than venom to kill their prey. However, because the patterns on their backs are similar to rattlesnakes and because they coil, vibrate their tails, and even strike when threatened, gopher snakes are often mistaken for rattlesnakes.

For more information about this beneficial snake, check out these resources:

http://web.cals.uidaho.edu/idahogardens/2012/08/gopher-snake/
http://imnh.isu.edu/digitalatlas/bio/reptile/serp/pica/picafram.htm
http://fieldguide.mt.gov/detail_ARADB26020.aspx#

I hope you found this information useful and enjoy this great little snake in your landscape.