Boa Vista is warm and sunny year-round, with temperatures ranging from around 22°C in January to 29°C in September. The trade winds blow consistently from the northeast, keeping the heat manageable and making conditions reliably good for windsurfing and kitesurfing — especially between November and June.
Rain is rare and brief; most years the island gets less than 100mm annually, and some years almost none at all. The Saharan harmattan occasionally blows in from the east between December and March, bringing dust haze that reduces visibility and makes the landscape feel even more like a desert.
Turtle season (June to October) is a compelling reason to visit. Loggerhead sea turtles come ashore at night to nest on the eastern beaches, and several conservation organisations offer guided nighttime turtle watches that do not disturb the animals. Boa Vista is one of the most important nesting sites for loggerheads in the entire Atlantic.
The quietest period for tourists is September and October — also peak turtle season and, conveniently, when water temperatures are warmest for swimming and snorkelling.