Sources: The Library of Congress Country Studies; CIA World Factbook
The far north is the only part of the country in which there is a large section of the Andean (plateau). The area receives considerable rainfall during the summer months in what is commonly known as the "Bolivian winter," forming shallow lakes of mostly saline waters that are home to a number of bird species, including the Chilean flamingo. Some of the water from the plateau trickles down the Andes in the form of narrow rivers, many of which form oases before being lost to evaporation or absorption into the desert sands, salt beds, and aquifers. However, some rivers do manage to reach into the Pacific, including the R�o Loa, whose U-shaped course across the desert makes it Chile's longest river. The water rights for one of the rivers, the R�o Lauca, remain a source of dispute between Bolivia and Chile. These narrow rivers have carved fertile valleys in which an exuberant vegetation creates a stark contrast to the bone-dry hills. In such areas, roads usually are built half way up the arid elevations in order to maximize the intensive agricultural use of the irrigated land. They offer spectacular panoramic vistas, along with the harrowing experience of driving along the edges of cliffs.
As in the for north, the coastal areas of the near north have a distinct microclimate. In those sections where the airborne moisture of the sea is trapped by high bluffs overlooking the ocean, temperate rain forests develop as the vegetation precipitates the vapor in the form of a misty rain. Because the river valleys provide breaks in the coastal elevations, maritime moisture can penetrate inland and further decrease the generally arid climate in those valleys. The higher elevations in the interior sections are covered with shrubs and cacti of various kinds.
Central Chile (Chile Central), home to a majority of the population, includes the three largest metropolitan areas-- Santiago, Valpara�so, and Concepci�n. It extends from about 32� south latitude to about 38� south latitude. The climate is of the temperate Mediterranean type, with the amount of rainfall increasing considerably and progressively from north to south. In the Santiago area, the average monthly temperatures are about 19.5� C in the summer months of January and February and 7.5� C in the winter months of June and July. The average monthly precipitation is no more than a trace in January and February and 69.7 millimeters in June and July. By contrast, in Concepci�n the average monthly temperatures are somewhat lower in the summer at 17.6� C but higher in the winter at 9.3� C, and the amount of rain is much greater. In the summer, Concepci�n receives an average of twenty millimeters of rain per month; in June and July, the city is pounded by an average of 253 millimeters per month. The numerous rivers greatly increase their flow as a result of the winter rains and the spring melting of the Andean snows, and they contract considerably in the summer. The combination of abundant snow in the Andes and relatively moderate winter temperatures creates excellent conditions for Alpine skiing.
The south is one of the rainiest areas in the world. One of the wettest spots in the region is Valdivia, with an annual rainfall of 2,535.4 millimeters. The summer months of January and February are the driest, with a monthly average precipitation of sixty-seven millimeters. The winter months of June and July each produce on average a deluge of 410.6 millimeters. Temperatures in the area are moderate. In Valdivia, the two summer months average 16.7� C, whereas the winter months average 7.9� C.
In the northern part of the far south, there is still plenty of rainfall. For instance, Puerto Ais�n, at 45�24' south latitude, receives 2,973.3 millimeters of rain per year. However, unlike in Valdivia, the rain falls more or less evenly throughout the year in Puerto Ais�n. The summer months average 206.1 millimeters, whereas the winter months average 300 millimeters. The temperatures at sea level in Puerto Ais�n average 13.6� C in the sum