Peru is one of the larger South American countries – some ten times the size of England – covering an area of 1,285,000 square kilometres and with a population of over 26 million. Around seventy percent of its inhabitants live in cities, which are mainly located along the coast and limited almost exclusively to half a dozen thin but relatively fertile river valleys running into the Pacific.
Peru is unique in possessing such a wide variety of ecosystems ranging from the dryest hot desert in the Americas, to the high Andean peaks (over 7600m above sea level); from a two- thousand-kilometre-long belt of cloud forest, rich in flora and fauna, to a vast area of lowland Amazon jungle, covering about half the country. The three main zones of Peru are known as La Costa (the coast), La Sierra (the mountains) and La Selva (the jungle). Within a matter of hours, you can leave the scorching desert coastline with some of the Pacific Ocean’s best fishing, cross the world’s highest tropical mountain range – the Andes – and plunge down into our planet’s biggest tropical rainforest.
The unusual weather conditions in Peru are created mainly by two major offshore ocean currents – the cold Humbolt Current coming up from Chile and the Antarctic, which meets the warm, tropical El Niño current coming down from the Pacific along the Ecuadorian coast. The Humbolt is largely responsible for the dry desert coastline of Peru and Northern Chile, sending Pacific clouds up into the Andes where they precipitate as rain. Traditional Peruvian wisdom says that it only really rains on the Peruvian coast about once every twenty years or so, when the El Niño current pushes further down the coast, warming the seas and causing disruptive rains in the desert. These rains bring devastating floods to towns and settlements poorly prepared for torrential downpours and often inhabited by migrants from the mountains. However, the rains also bring the desert into bloom as all the wild flower seeds, preserved by the drought conditions, suddenly burst into life. Over the last few years, the Peruvian weather has been rather unsettled and El Niño has been acting even more unpredictably than usual, possibly as a result of global warming. However, it still rarely rains on the coast, although the Lima region does experience substantial smog, coastal fogs or mists and even drizzle, particularly between the months of May and November.
The climate in the Sierra and Selva regions can be fairly clearly divided into a wet season (Oct-April) and a dry season (May-Sept). There is, of course, some rain during the dry season, but it is much heavier and much more frequent in the wet season, when travel becomes much harder: roads are often impassable, flights are frequently cancelled or delayed due to poor conditions, and landslides affect trains and bus routes alike. Trekking in the mountains and canoeing on the Andean or jungle rivers are also much less enjoyable during the wet season than at other times of year. Equally frustrating – especially if you’ve travelled halfway across the world to be here – is the fact that some of the stupendous views, particularly those around Cusco and in the Cordillera Blanca, are often obscured by clouds at this time of year. If you want to visit several different regions of Peru, then your best bet is to travel round in the middle of the dry season between June and September.
Again, weather conditions have been quite unsettled in these regions over the last ten years or so, with the Altiplano zone, around Puno, being affected by serious droughts , which have left the water level of Lake Titicaca at its lowest for years.