section: Geography
question: What regions get a lot of summer rain in Peru?
article: Peru
candidates: Peru covers of western South America. It borders Ecuador and Colombia to the north, Brazil to the east, Bolivia to the southeast, Chile to the south, and the Pacific Ocean to the west. The Andes Mountains run parallel to the Pacific Ocean; they define the three regions traditionally used to describe the country geographically. The "costa" (coast), to the west, is a narrow plain, largely arid except for valleys created by seasonal rivers. The "sierra" (highlands) is the region of the Andes; it includes the "Altiplano" plateau as well as the highest peak of the country, the Huascarán. The third region is the "selva" (jungle), a wide expanse of flat terrain covered by the Amazon rainforest that extends east. Almost 60 percent of the country's area is located within this region. Most Peruvian rivers originate in the peaks of the Andes and drain into one of three basins. Those that drain toward the Pacific Ocean are steep and short, flowing only intermittently. Tributaries of the Amazon River are longer, have a much larger flow, and are less steep once they exit the "sierra". Rivers that drain into Lake Titicaca are generally short and have a large flow. Peru's longest rivers are the Ucayali, the Marañón, the Putumayo, the Yavarí, the Huallaga, the Urubamba, the Mantaro, and the Amazon. Peru does not have an exclusively tropical climate; the influence of the Andes and the Humboldt Current cause great climatic diversity within the country. The "costa" has moderate temperatures, low precipitations, and high humidity, except for its warmer, wetter northern reaches. In the "sierra", rain is frequent during summer, and temperature and humidity diminish with altitude up to the frozen peaks of the Andes. The "selva" is characterized by heavy rainfall and high temperatures, except for its southernmost part, which has cold winters and seasonal rainfall. Because of its varied geography and climate, Peru has a high biodiversity with 21,462 species of plants and animals reported as of 2003; 5,855 of them endemic.