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

​2019
January 5 - Saturday - New at 5:28 PM
January 20 - Sunday - Full at 9:16 PM 
February 4 - Monday - New at 1:03 PM
February 19 - Tuesday - Full at 7:53 AM
March 6 - Wednesday - New at 8:03 AM
March 20 - Wednesday - Full at 6:42 PM
April 5 - Friday - New at 1:50 AM
April 19 - Friday - Full at 4:12 AM
May 4 - Saturday - New at 3:45 PM
May 18 - Saturday - Full at 2:11 PM
June 3 - Monday - New at 3:01 AM
June 17 - Monday - Full at 1:30 AM
July 2 - Tuesday - New at 12:16 PM
July 16 - Tuesday - Full at 2:38 PM
July 31 - Wednesday - New at 8:11 PM
August 15 - Thursday - Full at 5:29 AM
August 30 - Friday - New at 3:37 AM
September 13 - Friday - Full at 9:32 PM
September 28 - Saturday - New at 11:26 AM
October 13 - Sunday - Full at 2:07 PM
October 27 - Sunday - New at 8:38 PM
November 12 - Tuesday - Full at 5:34 AM
November 26 - Tuesday - New at 7:05 AM
December 11 - Wednesday - Full at 9:12 PM
December 25 - Wednesday - New at 9:13 PM