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Climate

The climate of Puerto Rico in the Köppen climate classification is mostly tropical rainforest. Temperatures are warm to hot year round, averaging near 85 °F (29 °C) in lower elevations and 70 °F (21 °C) in the mountains. Easterly trade winds pass across the island year round. Puerto Rico has a rainy season, which stretches from April into November, and a dry season stretching from December to March. The mountains of the Cordillera Central create a rain shadow and are the main cause of the variations in the temperature and rainfall that occur over very short distances. The mountains can also cause wide variation in local wind speed and direction due to their sheltering and channeling effects, adding to the climatic variation. Daily temperature changes seasonally are quite small in the lowlands and coastal areas.

Between the dry and wet seasons, there is a temperature change of around 6 °F (3.3 °C). This change is due mainly to the warm waters of the tropical Atlantic Ocean, which significantly modify cooler air moving in from the north and northwest. Coastal water temperatures during the year are about 75 °F (24 °C) in February and 85 °F (29 °C) in August. The highest temperature ever recorded was 110 °F (43 °C) at Arecibo, while the lowest temperature ever recorded was 40 °F (4 °C) in the mountains at Adjuntas, Aibonito, and Corozal. The average yearly precipitation is 66 in (1,676 mm).