It's always a good time to come and visit the Palace. November through May is considered 'dry season' and the temperatures range from 74-84°F, ocean temperatures from 79-84°F. June through September is considered 'green season' and temperatures range from 82-89°F, ocean temperatures from 82-86°F. Sept/Oct are more humid and rain is common, but not expected daily. Afternoon rains of 2-3 hours every few days.
For a weekly update go to: Manzanillo, Mexico Weather - The Weather Network