Due to climate warming trends, the USDA just updated U.S. garden hardiness zones. You can find the new information here:

http://planthardiness.ars.usda.gov/PHZMWeb/

Your hardiness zone determines which perennials will survive the winter and which annual vegetables and flowers should thrive.

From what I can tell on the map, we have moved from zone 4B to zone 5A. Doesn’t sound like much but it does give us additional options in terms of landscape plants. The change  could also explain why okra now grows well up here! I am hoping the warmer designation means I can grow tomatoes with less pampering.