page_title: Climate of Peru
section_title: The Pacific coastal desert
hierarchical_section_title: Climate of Peru / The Pacific coastal desert
caption_attribution_description: Photo by www.world-wide-gifts.com/
context_page_description: Climate of Peru describes the diverse climates of this large South American country with an area of 1,285,216 km². Peru is located entirely in the tropics but features desert and mountain climates as well as tropical rain forests. Elevations above sea level in the country range from −37 metres to 6,788 metres and precipitation ranges from less than 20 millimetres annually to more than 8,000 millimetres. There are three main climatic regions: the Pacific Ocean coast is one of the driest deserts in the world but with some unique features; the high Andes mountains have a variety of microclimates depending on elevation and exposure and with temperatures and precipitation from temperate to polar and wet to dry; and the Amazon Basin has tropical climates, mostly with abundant precipitation, along with sub-tropical climates in elevations above 1,550 metres.
context_section_description: The coastal desert of Peru extends unbroken from near the northern border with Ecuador to the southern border with Chile, a north to south distance of 1,600 kilometres (990 mi). Three names are sometimes applied to the desert in different parts of the coastline. The Sechura Desert is in northern Peru. Southward is the Peruvian coastal desert which becomes at an indefinite location the Atacama Desert which continues into Chile. The Sechura desert in the north is warmer and less impacted by the cloud cover that characterizes the more southern parts of the coastal desert, but there is a uniformity in precipitation along the 1,000 mile coastline with less than 30 millimetres (1.2 in) annually. The desert strip along the Pacific is narrow, at its widest about 120 km (75 mi) before the land climbs into the Andes and precipitation increases with elevation. 
  The following table summarizes climatic statistics for cities in the north, central, and southern parts of the coastal desert      
  A characteristic of the Peruvian coastal desert is low average temperatures despite its tropical latitudes. In the tropics the average annual temperature is usually at least 25 °C (77 °F) with little temperature variation among months. By contrast most of the Peruvian coastal desert has average annual temperatures of less than 20 °C (68 °F) and with temperatures falling to or near 10 °C (50 °F) during the Austral winter.  The relatively low temperatures of the Peruvian coastal desert are caused by the cold Humboldt Current. Ocean water temperatures in Lima in September, the coldest month, are as low as 14.4 °C (57.9 °F) similar to water temperatures near Los Angeles during its winter months.
  The cold waters of the Humboldt Current also create a moist fog called garúa in Peru. The cold water, especially in the Austral winter from May to November, cause an inversion, the air near the ocean surface being cooler than the air above, contrary to most climatic situations. During the Austral winter, the trade winds blow thick stratus clouds inland over coastal areas up to an elevation of 1,000 metres (3,300 ft) and the dense fog coalesces into drizzle and mist. In the austral summer from December to April, the weather is mostly sunny. 
   
  The moisturizing impact of the fog is increased by the high average humidity of the coastal deserts. For example, Lima has an average humidity of 84 percent, more than double the average humidity of most deserts. As a result of the fog, Lima gets only 1230 hours of sunshine annually, and less that 50 hours each in the months of July, Aug, and Sept.  (By contrast, Seattle, Washington, not noted for its sunny weather, gets 2,170 hours of sunshine annually and "foggy London town" gets 1,618 hours of sunshine annually.) 
  As elevation increases moving inland from Lima and other coastal locations, so also does precipitation.  Chosica, 50 kilometres (31 mi) inland from the Pacific at an elevation of 835 metres (2,740 ft) gets 109 millimetres (4.3 in) annually of precipitation compared to Lima's precipitation of 16 millimetres (0.63 in). Matucana, 80 km (50 mi) inland at an elevation of 2,464 m (8,084 ft) gets 479 mm (18.9 in) of precipitation.
  Apart from the irrigated agriculture in 57 river valleys coming down from the Andes and passing through the desert en route to the ocean, the coastal desert is almost without vegetation. In a few favored locations, where mountains come close to the sea and the fog condenses on the mountain slopes, the garúa permits vegetation to thrive in "fog oases," called lomas in Peru. Lomas range in size from very small to more than 40,000 hectares (99,000 acres) and their flora includes many endemic species.Scholars have described individual lomas as "an island of vegetation in a virtual ocean of desert."Peru has more than 40 lomas totalling in area less than 2,000 square kilometres (770 sq mi) out of a total coastal desert area of 144,000 square kilometres (56,000 sq mi).
caption: Most of the coastal desert is devoid of vegetation.
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