The GardenZeus California Climate Zones were created to allow GardenZeus.com to offer our uniquely customized gardening information, and automatically generated monthly tips and task lists, across a large and climatically diverse state. Gardening expert C. Darren Butler took into account many factors while developing the GardenZeus California Climate Zones, such as seasonal climate, elevation, temperature averages and extremes in both summer and winter, frequency of frosts, and precipitation. USDA Plant Hardiness Zones were not sufficient for the purposes of GardenZeus.com because they take into consideration only the lowest annual temperature, which puts most of California into a few zones. Sunset Zones presented the opposite problem: since we're developing unique data, and a lot of it, for each climate zone, the 19 Sunset Zones that occur in California are just too many zones. For GardenZeus.com, our 15 climate zones for California, like the third bed for Goldilocks, are just right.