The Commonwealth Caribbean islands make up a large subcomponent of the hundreds of islands in the Caribbean Sea, forming a wide arc between Florida in the north and Venezuela in the south, as well as a barrier between the Caribbean Sea and the Atlantic Ocean. Varying considerably in size, the islands, which are the isolated upper parts of a submerged chain of volcanic mountains, are scattered over thousands of square kilometers of sea. The entire region lies well within the northern tropics.
The Caribbean climate is tropical, moderated to a certain extent by the prevailing northeast trade winds. Individual climatic conditions are strongly dependent on elevation. At sea level there is little variation in temperature, regardless of the time of the day or the season of the year. Temperatures range between 24°C and 32°C. In Kingston, Jamaica, the mean temperature is 26°C, whereas Mandeville, at a little over 600 meters high in the Carpenters Mountains of Manchester Parish, has recorded temperatures as low as 10°C. Daylight hours tend to be shorter during summer and slightly longer during winter than in the higher latitudes. The conventional division, rather than the four seasons, is between the long rainy season from May through October and the dry season, corresponding to winter in the northern hemisphere.
Hurricanes are a constant feature of most of the Caribbean, with a "season" of their own lasting from June to November. Hurricanes develop over the ocean (usually in the eastern Caribbean) during the summer months when the sea surface temperature is high (over 27°C) and the air pressure falls below 950 millibars. These conditions create an "eye" about 20 kilometers wide, around which a steep pressure gradient forms that generates wind speeds of 110 to 280 kilometers per hour. The diameter of hurricanes can extend as far as 500 to 800 kilometers and produce extremely heavy rainfalls as well as considerable destruction of property. The recent history of the Caribbean echoes with the names of destructive hurricanes: Janet (1955), Donna (1960), Hattie (1961), Flora (1963), Beulah (1967), Celia and Dorothy (1970), Eloise (1975), David (1979), and Allen (1980).
Library of Congress Country Studies, 12/2007