Port Louis is hot, low, and humid year-round, and noticeably more sticky than the cooler upland towns of Curepipe and Quatre Bornes. The best months to visit are May to October, the southern winter, when daytime temperatures sit around 22–27°C and the humidity drops.
November to April is the rainy and cyclone season. Heavy showers are common, often short but tropical; cyclones occasionally close roads, ports, and the airport between January and March. If you're visiting at this time, keep an eye on forecasts and build in flexibility.
The big event in the city is the racing season at Champ de Mars, late March or April through November, with the most prestigious meetings (Maiden Cup, Duchess of York Cup) in late August and September. Chinese New Year in Chinatown (late January or February) and Cavadee (the Tamil festival, January or February) are both visible in the streets.