Small areas with peculiar microclimates often exist within a zone. The areas are colder or milder than the surrounding area. The zone lines are arbitrarily drawn and the zones merge gradually into each other. Conditions near the border of one zone may closely approximate those of an adjacent zone.
I have pinpointed the zone where I live. Toronto, Ontario is designated as Zone 6b. This is a good time to locate your area on the map and establish your zone for future reference.