It's best to begin painting in the morning on a clear, dry day when there is no danger of morning dew settling on the surface. You should also avoid painting in windy conditions or in direct sunlight. Be sure you finish applying the last coat of paint so it has time to dry before temperatures drop and dew sets in. Any condensation that settles on the uncured paint will decrease the glossiness of the finish.
Before painting, check the weather to find out if the temperature and humidity conditions match the marine paint manufacturer's specifications. The temperature includes that of the ambient air, substrate, and paint. Staying within the manufacturer's guidelines for humidity, temperature and dew point helps ensure proper drying and maximum gloss.