There are 58 counties in California and 78 fairs operated under the guidelines of the Department of Food and Agriculture - Division of Fairs and Expositions. This agency also manages the permitting of horse racing operations (see horse racing and wagering fairs.)
Among the California State fairs, there are some operated by the State of California, more operated by California counties, and several citrus fairs.
This official agency for oversight of fairs in California has a list of 78 fairs operating annually, with some counties hosting several fairs and larger counties such as Los Angeles having three fairs in three diverse regions.
Fairs celebrate community heritage, they allow all ages to compete in a variety of events, hold family reunions, display and view artwork, learn about other cultures, premier new inventions and showcase the best of California. Many fairs offer free tours to schools, free youth admission on certain days, and valuable educational experiences throughout the year.
County fairs typically include farm animals in petting zoos, and competitions in raising livestock and animals, as well as featured animal exhibitions. The state fairs also follow a format of showcasing each region's agricultural assets, as well as providing contests ranging from cooking and recipes to crafting and art.
County fairs generally are held once in a year and the average length of a fair is around 3 - 5 days, though the larger fairs actually are held for over a month.
The largest and most attended fair is the Los Angeles County Fair held at Fairplex in Pomona. Top attendance fairs include San Diego Fair at Del Mar, Orange County Fair in Costa Mesa, and California State Fair in Sacramento. San Diego Fair gets close to 1.4 million attendance..
The fair season launches in February with the Indio Date Festival and Riverside County Fair. The event is unique and features a desert theme. The fair season runs through October, with a few fairs in November. The state and county fairs don't hold events in December, in general.
However, there are many fairs that do have December events such as the Great Dickens Fair at the Cow Palace in the San Francisco Bay Area.
Here are some archived California State Fair dates.