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

​2018
​January 1 - Monday - Full at 6:24 PM (Super Full Moon)
January 16 - Tuesday - New at 6:17 PM
January 31 - Wednesday - Full at 5:26 AM (Blue Moon, Lunar Eclipse)
February 15 - Thursday - New at 1:05 PM
March 1 - Thursday - Full at 4:51 PM
March 17 - Saturday - New at 6:11 AM
March 31 - Saturday - Full at 5:36 AM (Blue Moon)
April 15 - Sunday - New at 6:57 PM
April 29 - Sunday - Full at 5:58 PM
May 15 - Tuesday - New at 4:47 AM
May 29 - Tuesday - Full at 7:19 AM
June 13 - Wednesday - New at 12:43 PM
June 27 - Wednesday - Full at 9:53 PM
July 12 - Thursday - New at 7:47 PM (Super New Moon)
July 27 - Friday - Full at 1:20 PM (Micro Full Moon)
August 11 - Saturday - New at 2:57 AM
August 26 - Sunday - Full at 4:56 AM
September 9 - Sunday - New at 11:01 AM
September 24 - Monday - Full at 7:52 PM
October 8 - Monday - New at 8:46 PM
October 24 - Wednesday - Full at 9:45 AM
November 7 - Wednesday - New at 8:01 AM
November 22 - Thursday - Full at 9:39 PM
December 6 - Thursday - New at 11:20 PM
December 22 - Saturday - Full at 9:48 AM