The WORLD GUIDE says:

"One particular climatic feature sets the Indian Ocean apart: all the spots enjoy a subtropical or tropical climate and, apart from the ocean regions around South Australia, Indian Ocean coasts are exclusively warm water areas. Of course there are regional differences (like a warmer tendency to the north) and cloudy, rainy days with more windchill, but water temperatures between 23°C and 30°C and daytime highs from 25°C to well over 30°C mean no-one really gets cold! A large part of Madagascar and the Mascarenhas Archipelago, to which La Réunion and Mauritius belong, lie almost permanently under the influence of... " world guide