Climate zones are used as a tool for gardeners and orchardists to guide in selecting appropriate trees for particular areas. The climate zones are determined by average minimum yearly low temperatures. This is only a general guide because your own individual location (microclimate) has a significant influence that the general zones neglect to recognize. These variations may suggest that the zone adjacent to you may be more appropriate.
The following link to the National Gardening Association's USDA Hardiness Zone Finder is provided to assist you in deciding which zone you are in. Simply plug your zip code into the search engine.
The National Gardening Association USDA Hardiness Zone Finder