California Code, Education Code - EDC § 37202

(a) Except if a school has been closed by order of a city or a county board of health, or of the State Board of Health, on account of contagious disease, or if the school has been closed on account of fire, flood, or other public disaster, the governing board of a school district shall maintain all of the elementary day schools established by it for an equal length of time during the school year and all of the day high schools established by it for an equal length of time during the school year.

(b) Notwithstanding subdivision (a), a school district that is implementing an early primary program, pursuant to Chapter 8 (commencing with Section 8970) of Part 6, may maintain kindergarten or transitional kindergarten classes for different lengths of time during the schoolday, either at the same or a different schoolsite.