Weather map in the region of the Atlantic Ocean

Weather map in the region of the Atlantic Ocean

The climate of the Caribbean is regulated mainly by the amount of solar radiation the region receives throughout the year. There are other factors that contribute to regulating the tropical climate, such as the trade winds (the dominant winds throughout the tropical region, between 23.5 degrees north and 23.5 degrees south latitude). The trade winds are created by two main factors, the rotation of the Earth and the temperature difference between the tropics and the poles. Another extremely important phenomenon is El Niño, an unusual warming of the waters of the Pacific Ocean that produces certain effects in the Caribbean climate. In addition to these phenomena, there is also the huge mass of warm water that accumulates annually between the Caribbean Sea and the Gulf of Mexico.

The Caribbean region is affected each year by various climactic phenomena. The most important of these are tropical cyclones. The hurricane season extends from June 1 to November 30. These systems affect the entire region, leaving huge losses of lives and property in their wake. In general, the region’s climate is humid with an average temperature between 18 and 22 ºC in the winter and 26 to 35 ºC in summer.

Precipitation in the Caribbean is caused by two main factors: cyclonic systems and the rain produced by convective systems fed by local winds and the orography (hills and mountain ranges) of the islands. The months with the least precipitation are December, January, February and March. Precipitation begins to increase in May, and although there is generally a decrease during the months of June, July and August, the amount of rain begins to rise again in September, October and November.

Puerto Rico’s Climate 

Puerto Rico is the smallest and easternmost island of the Greater Antilles. It is bordered on the north by the Atlantic Ocean, on the south by the Caribbean Sea, to the west by the Mona Channel, and to the east lie the British Virgin Islands and to the southeast lie the U.S. Virgin Islands. Puerto Rico is an archipelago consisting of the island of Puerto Rico and various islands, islets and keys, among which are the islands of Mona, Monita, Vieques, Culebra, Desecheo and Caja de Muertos. Its geographic location (18.5 N latitude and 66.5 W longitude) means it is strongly affected by the trade winds.

The ocean’s influence, solar heating, and the topography and mountainous configuration of the island, dominated by the Central Mountain Range — with elevations up to 4,280 feet (1,338 m) — make up the island’s climactic system. Among the important influences are the winds over ocean and land, as well as the winds in the valleys and mountains of the interior of the island.

The eastern region, where the Caribbean National Forest, El Yunque, is located, has a tropical rainy climate and receives the greatest amount of rain, approximately 200 inches more than the rest of the island. The north, which has a subtropical climate, is generally rainy throughout the year, with temperatures ranging between 24 and 34 °C (75 to 93 °F). The south is the driest area, with a semi-desert climate. The Guánica dry forest, where temperatures reach 100 °F (37.7 °C) in the summer, is located here. The south receives little rain. The summer has some rain and is very warm, and the heat index can reach up to 115 °F (46.1 °C). The west is rainy in the summer and less rainy in the winter, but it is cooler in the winter and temperatures can drop to 50 °F (10 °C). The center of the island is very mountainous, rainy and cooler, with temperatures that can fall as low as 40 °F (4.4 °C) and a climate that ranges from subtropical to temperate in areas where the elevation exceeds 3,000 feet (914.4 meters) above sea level.

The mountainous center of Puerto Rico is the rainiest and coolest area. It has two seasons: a dry season and a rainy season. The dry season runs from December to April and the rainy season from May to September. The average annual precipitation on the island is 55 to 80 inches (139.7- 203.2 cm). Precipitation decreases significantly during the months from December to April, especially in the southern part of the island where the sun’s intensity causes evapotranspiration (the loss of moisture by plants due to evaporation) to reach elevated levels, increasing the possibility of forest fires on the southern slopes.

Tropical storms and hurricanes affect Puerto Rico every summer and autumn, causing flooding and landslides. August and September are the most active months. Among the hurricanes that affected Puerto Rico in recent years are: Hugo in 1989, Hortense in 1996 and Georges in 1998. These systems generate huge amounts of rain and runoff on the island that are positive in that they feed the rivers, reservoirs, aquifers and wetlands. But in some cases the impacts are negative when they cause floods and landslides that cause serious loss of life and property.

Author: Rafael Méndez Tejada
Published: December 27, 2011.

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