California Code, Elections Code - ELEC § 10733

(a) In the event of a catastrophe that causes a vacancy in at least 101 of the offices of the United States House of Representatives, including at least one of the offices representing California, a special election to fill a vacancy in the office of Representative in Congress shall be conducted on a Tuesday not more than 49 days following the announcement of the vacancy by the Speaker of the United States House of Representatives pursuant to subsection (b) of Section 8 of Title 2 of the United States Code. Notwithstanding Section 10732, the Governor shall issue a proclamation calling the special election within one day of the Speaker of the United States House of Representatives announcing the vacancy. In the event of a catastrophe that causes a vacancy in at least one-fourth of the total offices of the United States House of Representatives representing California but not a vacancy in at least 101 of the offices of the United States House of Representatives, the special election shall occur on a Tuesday not more than 49 days following the issuance of an election proclamation by the Governor.

(b) A special election may be conducted within 75 days following the proclamation in order that the special election may be consolidated with the next regularly scheduled statewide election or local election occurring wholly or partially within the same territory in which the vacancy exists, provided that the voters eligible to vote in the local election comprise at least 50 percent of all the voters eligible to vote on the vacancy.

(c) A special election to fill a vacancy caused by a catastrophe that causes vacancies in at least 101 of the offices of the United States House of Representatives pursuant to subdivision (a) shall not be conducted if any of the following is scheduled to occur within 75 days of the Speaker of the United States House of Representatives calling the vacancy: