Geography of Dominica - Climate

Climate

The island's climate is tropical, moderated by northeast trade winds and heavy rainfall.

Dominica has a tropical wet climate with characteristically warm temperatures and heavy rainfall. Excessive heat and humidity are tempered somewhat by a steady flow of the northeast trade winds, which periodically develop into hurricanes. The steep interior slopes also alter temperatures and winds. Temperature ranges are slight. Average daytime temperatures generally vary from 26 °C (78.8 °F) in January to 32 °C (89.6 °F) in June. Diurnal ranges are usually no greater than 3 °C (5.4 °F) in most places, but temperatures dipping to 13 °C (55.4 °F) on the highest peaks are not uncommon.

Most of the island's ample supply of water is brought by the trade winds. Although amounts vary with the location, rain is possible throughout the year, with the greatest monthly totals recorded from June through October. Average yearly rainfall along the windward east coast frequently exceeds 5,000 mm (196.9 in), and exposed mountainsides receive up to 9,000 mm (354.3 in), among the highest accumulations in the world. Totals on the leeward west coast, however, are only about 1,800 mm (70.9 in) per year. Humidities are closely tied to rainfall patterns, with the highest values occurring on windward slopes and the lowest in sheltered areas. Relative humidity readings between 70 percent and 90 percent have been recorded in Roseau.

Hurricanes and severe winds, most likely to occur during the wettest months, occasionally are devastating. The most recent hurricanes of note were David and Frederic in August 1979 and Allen in August 1980. The 1979 hurricanes caused over 40 deaths, 2,500 injuries, and extensive destruction of housing and crops. Many agricultural commodities were destroyed during the 1980 storm, and about 25 percent of the banana crop was destroyed by strong winds in 1984.

Dominica is especially vulnerable to hurricanes as the island is located in what is referred to as the hurricane region. In 1979, Dominica was hit directly by Category 5 Hurricane David, causing widespread and extreme damage. On August 17, 2007, Hurricane Dean, a Category 1 at the time, hit the island. A mother and her seven-year-old son died when a landslide caused by the heavy rains fell onto their house. In another incident two people were injured when a tree fell on their house. Prime Minister Roosevelt Skerrit estimated that 100 to 125 homes were damaged, and that the agriculture sector was extensively damaged, in particular the banana crop.