Normal
I have been on 15 Mexican Riviera cruises and 12 out of San Diego. And all times of the year. ( January, March, April, August and September) . I was on the Mercury last March for a 10 day cruise. Every time the ship heads North back to San Diego the seas get choppy.. We made friends on that last cruise and two wives from our table never made it to dinner the last night. And my wife and I did not think it was too "rocky". I have been on a huge ship (Star Princess) and a small ship (Ryndam) and it never fails to get choppy as we head back to San Diego. Everyone has a different tolerance to sea sickness. My wife always has some patches ready to put on.