Hi Linda,
One of the most specific sites that I'm aware of is the American Horticultural Society and their Heat Map. If you copy and past the link below then you can put in your zip code to find your zone. There are several microclimates in San Diego that will vary a bit, however this should be helpful for understanding your area. http://www.ahs.org/publications/heat_zone_finder.htm

The Western Outdoor Sunset zone maps, which cover 13 Western states, are much more precise than the USDA's, since they factor in not only winter minimum temperatures, but also summer highs, lengths of growing seasons, humidity, and rainfall patterns to provide a more accurate picture of what will grow there.

Since you live in the western U.S., you'll find that nurseries and gardeners usually refer to the Sunset climate zones rather than the USDA plant hardiness zones. The Sunset zones and maps are what's listed for plants in Sunset's Western Garden Book which is considered the standard gardening references here in the West. aka respectfully referred by many as the Gardening Bible and well worth the valuable knowledge for plants, pests and more as a reference.

About your second question: are you referring to your grass in your yard or different plants? I would need more information to answer this question. Thanks. VaNessa