Peter, I believe you're being flippant for the sake of being flippant. I assume you're alluding to the trope of desert islands being little palm tree studded areas of tropical idyll. There are islands off the coast of Antarctica where the environment is considered desert, but would be far from the climate of an island in the Bahama region. Plus such islands are often stuck with hurricanes/typhoons depending on locale. So, I don't really know what to expect from a desert island. As such you should probably pack a cagoule. Just in case.
EDITED: 6 Feb 2020 16:26 by GRAPHITONE