On the whole the tropical climate throughout the island is temperate all year and the trade winds ensure the temperature stays pleasant. The months between December and April tend to be the regions busiest, attracting travellers from all over the world. Summer months in Grand Cayman reach 30°C and the humidity is often high but the North East trade winds are identified for bringing the temperature to a more comfortable level.
For the many divers this is the perfect time to visit as the sea gives high temperatures soothing seas and superior underwater visibility. A typical rainy seasons runs from May to November, even throughout the coolest periods of winter the climate alternates by only a few degrees from month to month and winter remains hot and dry with a dependable record of sunshine.
This winter climate enjoys temperatures of 27°C. Sea temperatures stay put and steady all year round; they generally range between 22°C – 24°C with outstanding visibility even during rainfall. The ocean is normally calm and placid all year making the island not just an ideal diving location but also perfect for relaxation on the beach (Source holiday-weather.com)