No classes on full or new moons.  
Times given are specific to Santa Cruz:

2023
January 6 - Friday - Micro Full Moon, 3:07 PM
January 21 - Saturday - Super New Moon, 12:53 PM
February 5 - Sunday - Micro Full Moon, 10:28 AM
February 19 - Sunday - Super New Moon, 11:05 PM
March 7 - Tuesday - Full Moon, 4:40 AM
March 21 - Tuesday - New Moon, 10:23 AM
April 5 - Wednesday - Full Moon, 9:34 PM
April 19 - Wednesday - New Moon, 9:12 PM
May 5 - Friday - Full Moon, 10:34 AM
May 19 - Friday - New Moon (Black Moon), 8:53 AM
June 3 - Saturday - Full Moon, 8:41 PM
June 17 - Saturday - New Moon, 9:37 PM
July 3 - Monday - Full Moon, 4:38 AM
July 17 - Monday - New Moon, 11:31 AM
August 1 - Tuesday - Super Full Moon, 11:31 AM
August 16 - Wednesday - Micro New Moon, 2:38 AM
August 30 - Wednesday - Super Full Moon (Blue Moon), 6:35 PM
September 14 - Thursday - New Moon, 6:39 PM
September 29 - Friday - Full Moon, 2:57 AM
October 14 - Saturday - New Moon, 10:55 AM
October 28 - Saturday - Full Moon, 1:24 PM
November 13 - Monday - New Moon, 1:27 AM
November 27 - Monday - Full Moon, 1:16 AM
December 12 - Tuesday - New Moon, 3:32 PM
December 26 - Tuesday - Full Moon, 4:33 PM