Réunion has a hot sub-tropical climate with sea temperatures that rarely drop below 23°C. The dry season is May to October, with temperatures 20-25°C.
November to March is more humid, with most rain and occasional cyclones in January and February. The interior uplands have an almost temperate climate.
It can be cool in the mountains and it's advisable to have some warm clothing for the evenings. In October 2006 it did actually snow on the Piton des Neiges which is over 3,000 metres high.