At a latitude stretching from 12° to 25° south, Madagascar is well inside the tropics at its northern end and just outside the Tropic of Capricorn in the far south. Mexico and Queensland lie on similar latitudes.
With its climate dominated by the Indian Ocean’s southeastern trade winds, the island has a clear seasonal cycle. A hot, wet summer – between November and March – brings anything up to 4m of drenching rain to the eastern slopes and highlands, roughly four times the UK’s typical annual rainfall in the space of a few months. This is the season when ferocious cyclones hit the east coast and ravage their way inland – busting bridges, sweeping away roads and riverbanks and making travel extremely difficult. The rains are heavy but much less voluminous in the west and southwest of the island: and down in the semi-desert of the far southwest they don’t always do much more than spatter the parched earth. For the rest of the year, roughly from April to October, Madagascar experiences a dry, cool season – what naturalists call the austral winter. Overall, this is the best time to visit Madagascar: days are bright and usually warm to very warm and nights mild. Temperatures are highest at sea level and also higher in the north and on the west coast. The south can be much chillier: July in Fort Dauphin will have you glad of a fleece and an extra blanket at night.
For particular activities, bear the following in mind. In the highlands, above about 2000m, it can rain at almost any time of year and nights at high altitude can be bitterly cold, though freezing temperatures are rare. If you’re doing some hiking or climbing, you will need warm layers. It also tends to rain heavily most months in the northeast of the island, with the Masoala Peninsula and Baie d’Antongil like a greenhouse most of the year. Natural history enthusiasts should know that during the austral winter trees lose their leaves, animals are less active and some species hibernate, though whale-watchers can enjoy a continuous regatta of humpbacks up the east coast (and to a lesser extent the west) during their June-to-September northerly migration past the island. November is often recommended as a good time for wildlife, with the first rains bringing out an explosion of courting, mating and spawning among amphibians, reptiles, birds and the fabulous fossa. Diving and snorkelling are best at the end of the dry winter season, roughly from August to October, when the sediment brought down by the rivers during the rains has had time to disperse and settle.