When you visit Peru, one of the first things you’ll hear from the locals is that the country has three geographic zones: costa, sierra, y selva—coast, mountains, and jungle. Each zone has its own distinctive climate, so it’s a good idea to familiarize yourself with the latter when planning your trip.
The weather along the coast is generally moderate. This may seem strange, considering the area is basically desert, but its due in part to the cold Humboldt Current that flows along the shore. This means that the weather in cities like Lima and Trujillo hovers between 60 and 80 degrees all year, with almost no rain. In summer (December to March), there are warm days with strong sunshine, but in the winter a coastal fog called la garúa sets in and makes everything gray.
Weather in the sierra consists of wet and dry seasons; the former runs from November to March, the latter from May to September. The days are generally bright and clear, but at night, temperatures can dip down below zero, especially on the southern altiplano (Andean plateau), so you’ll need a warm jacket. Also, beware of sudden rainstorms, which can spring up quickly during the wet season. Fortunately, the sierra’s peak tourist period (June to August), with its numerous festivities, coincides with the dry season, so North Americans and Europeans who go during their summer vacation should have no problems.
The jungle, too, has wet and dry seasons, with strong heat and humidity year round. Generally the months from June to September are the best time to go, since wildlife-viewing opportunities will be reduced during times of heavy rain. Landslides and flooding are also a problem from January to April; plan accordingly.
Average monthly temperatures (°F) and rainfall (inches) for select locations in Peru are shown below.