Peru is a country of varied climate. Coast, Desert, Mountain, Jungle. Because of the influence of the cold Peruvian Oceanic Flow there is a dramatic change from the near-coast desert climate to the inland tropical valleys and then the high mountains of the Andes Range.
1 - The Peruvian Oceanic Flow
About 200 km wide,
south to north
just off the coast , is a large mass of cold water. This
current cools the air. Because such cool air cannot hold much
moisture, little rain falls in the region (includes Lima, capital
So, while leading
to stable atmospheric conditions, the
result is also a lack of rain on the coast of
fact, southern coastal Peru is one of the driest places on
At irregular periods,
usually every two to seven years, the northward
Peru Current weakens and the El Niño current of the equatorial zone
with its warm waters flows southward along the coast. This can have a
powerful effect on the climate in Peru, especially of Northern Peru.
2 - The El Niño
The El Niño ("the child"
in Spanish) phenomenon usually occurs
around Christmas, and so the name, referring to the Christ child.
creates changes in the atmosphere that lead to torrential
downpours in the usually dry region, upsetting the normal Peru climate.
1998, the El Niño phenomenon dumped tons of rain on the
desert in Northern Peru. The result? The second largest lake in Peru,
measuring 90 miles [145 kilometers] long and 20 miles [30 kilometers]
wide but only an average of 10 feet deep.
The changes caused by the El Niño can also disrupt marine life
and have had a very negative effect on the local fishing industry. This
is really noticeable in a town where we lived for 18 months, Los Organos.
Previously, many people along the northern coast region were employed
mainly in the jumbo squid fisheries but have suffered during the
frequent El Niños during the last several decades.
3 - The South Pacific Anticyclone
This is a high pressure system
movement from south to north that collects moisture and takes
to the coast. The climate in Peru along the coast is a result of this
air mass plus other factors such as the Peru Current (or Humbolt
Although not enough to bring rain, the moisture often
condenses into clouds or fog. This brings the persistent
in most of Coastal Peru from May to October with a somewhat high atmospheric
An area of closed,
circular fluid motion rotating in the same direction as the
Earth. This is usually characterized by inward spiraling winds
that rotate counter clockwise in the Northern Hemisphere and
clockwise in the Southern Hemisphere of the Earth. Most
large-scale cyclonic circulations are centered on areas of low
Anticyclone: An anticyclone (that is, opposite to a
cyclone) is a weather phenomenon defined by the National Weather Service's glossary as "A large-scale
circulation of winds around a central region of high atmospheric
pressure, clockwise in the Northern Hemisphere, anticlockwise in the
4 - The South Atlantic Anticyclone
Situated near the Argentinian coast, this consists of humid air masses which affect southeast Peru, causing rain in the southern Andean flank.
Between May and September, Peru climate sudden drops in temperature as this frigid air mass moves north. These cold fronts, lasting one or more days, are known as "surazos" or "big southerns."
5 - The Equatorial Cyclone
Located in the Amazon basin, this is a huge low pressure air mass. The air is warm and moist and the result is the large amount of rainfall and warm weather on the forest floor.
The 5 weather phenomena listed above are the factors that create the huge diversity in Peru climate zones, and the overall climate in Peru.
A - The Coast (La Costa)
* General Coastal Peru Climate:
Weather semiwarm and very dry or desert with very little rainfall,
about 150 mm (5.9 inches) per year. This involves the coast from sea
level to 2,000 meters (6,600 feet) and is characteristically barren.
* Northern Coastal Peru Climate: Very
dry warm climate on the northern coast (Piura and Tumbes) and up to
about 1,000 meters (3,300 feet.) Dry with low rainfall of 200 mm (8
inches) per year, and temperatures average 24 degrees C (75 F). (see Los Organos and Mancora)
B - Mountains (La Sierra)
* Temperate sub-humid:
In the mountains between 1,000 and 3,000 meters, with temperatures
around 20 degrees C (60 F) and rainfall between 500 and 1,200 mm (20 to
42 inches) per year.
* Cold Climate:
Typical of the Andean valleys between 3,000 and 4,000 meters. The
average rainfall is 700 mm (28 inches) per year and average
temperatures around 12 degrees C (53 F) down to freezing during the
* Weather frigid or 'puna':
Between 4,000 and 5,000 meters. With average rainfall of 700 mm (28
inches) and average temperatures of 6 degrees C (43 F). Summers are
rainy and winters are dry.
* Snow or icy Weather:
Above 5,000 meters with temperatures below 0 degrees C (32
F). This Peru climate is found in the high peaks with snow.
C - The Jungle (La Selva)
* Mid warm humid climate:
On the eastern slopes of the Andes, rainfall is about 2,000 mm (79
inches) per year and temperatures below 22 degrees C (72 F). There are
* Weather warm tropical moist or
wet: Predominates in the lowland rainforest (see Iquitos, upper Amazon). The rainfall
is around 2,000 mm (79 inches) per year, and temperatures average 25
degrees C (75 F) with extremes above 32 degrees C (90 F).
The variety in Peru
climate allows for high biodiversity and production.