Reunion’s climate is tropical, with temperatures varying according to elevation. Humidity is generally high. There is not a big temperature range between the seasons, but the year can be divided into summer and winter: November to April is hot and rainy, while May to November is usually dry and cooler, and is the most popular time for travel to Reunion. In Saint-Denis the summer temperatures average between 73°F (23°C) and 84°F (29°C), and in winter temperatures average between 64°F (18°C) and 75°F (24°C). Rain patterns vary hugely according to region, with the east of the island much wetter than the west. The cyclone season runs from mid-November to mid-April and the island is occasionally affected.
** Due to global warming the above is a guideline – Reunion Island is an all year round destination**
Here are some great websites if you want to check the weather before your trip: