 It lies in the USDA Plant Hardiness Zone "9b", where the average annual minimum temperature is 25-30 °F (-3.9 °C to -1.1 °C).The last measurable snow in the county fell in 1977, but snow flurries and sleet fell on January 8, 2010 over the course of an hour on an exceptionally cold day.During the summer rainy season from June to September, sea breezes from both coasts move inland, where the moist air is heated and rises to form thunderstorms.