Comores

The climate of the Comoro Islands, an archipelago in the Indian Ocean south of the Equator, is tropical, with a hot and rainy season from December to April, when the north-west monsoon prevails, and a relatively cool and dry season from May to November, when the south-east trade winds blow. The warmest period is from January to April, with an average daily temperature around 27°C, while the coolest months are July, August and September, when the average drops to around 23°C.

Of the three main islands that make up the archipelago, the two smaller ones (Mohéli and Anjouan) are occupied by hills in the interior, while the largest one, Grande Comore or Ngazidja, is home to the 2,360 meters high Karthala volcano, . The slopes enhance cloud formation, which can lead to showers and thunderstorms, especially on the main island, which, in fact, is the rainiest. On Mount Karthala, up to 5,000 millimeters of rain fall per year, while Moroni, which is located on the windward side in the rainy season (that is, it is exposed to the north-west monsoon), receives 2,700 mm of rain per year.

In Fomboni, on the island of Mohéli, total annual rainfall is 2,100 mm, while Ouani, on the island of Anjouan (also known as Nzwani), receives 1,800 mm of rain per year. January is the rainiest month throughout the archipelago, with more than 300 mm of rain along the coasts, while the driest month in Moroni is October, with 95 mm of rain, which shows that showers and thunderstorms can occur quite frequently even in the dry season, at least on the main island. However, these rains, though intense, are short-lived, and they usually soon make room for the sun. On the smaller islands, during the dry season, showers are less frequent and less intense.

Despite the rains, the Comoros suffer from a shortage of fresh water due to the absence of rivers.  The amount of sunshine in the Comoros is not exceptional, nor scarce. The sun shines for a few hours a day even in the wettest months. The sunniest period is that of the trade winds, ie May-November, when, however, a bit of cloudiness can form, especially near the mountains.