California Code, Elections Code - ELEC § 15

Notwithstanding any other provision of law, if the last day for the performance of any act provided for or required by this code shall be a holiday, as defined in Chapter 7 (commencing with Section 6700) of Division 7 of Title 1 of the Government Code, the act may be performed upon the next business day with the same effect as if it had been performed upon the day appointed.

For purposes of this section, the Friday in November immediately after Thanksgiving Day shall be considered a holiday.