The USDA has released a new hardiness zone map for the US. It's nice and interactive. At their site you can click on your state to enlarge. More information was taken into account in forming this map, such as proximity to bodies of water, and I believe even the micro climates found in heavily paved areas. People who live in cities can get temps 10F higher than what they're supposed to due to all the pavement around.
Despite the warming trend seen here this does not change your last expected frost date. I know a lot of people think it does though. And they might get away with planting things early but not becuase of this chart. Rather becuase we're in a La Niña year. Even so it's a good idea to protect your investment. Start saving plastic soda bottles or plastic containers and cut off the bottoms for a simple easy plant cover early on. This will protect from frost should a freeze head your way.