The island has a humid subtropical climate which is influenced by both the Golf current and north-easterly winds. There are two well defined seasons: the dry or winter from November to April and the rainy or summer from May to October, with mild cool breezes the year long. The mean annual rainfall is 1,375 mm (48 inches). Approximately 30% of the rainfall occurs during the winter and 70% during the summer and is more abundant in the western region of the country. The mean annual temperature ranges from 26 y 28? C , with exception of the plains or flatlands, where the temperature is usually higher, and the mountains, where the mean temperature is less than 26? C (values can drop to values below 20? C Sierra Maestra mountains).
The summer months are extremely hot, although winter is short and pleasant. Spring is almost a perennial season throughout the archipelago. The eastern region of the country is warmer that the western. There are very little temperature variations in the coastal region between day and night as opposed to the hinterland. During winter, masses of cold air affect the island, usually of short duration. The hurricane season begins in June and ends in November, however, September and October are considered the most dangerous months, because of the frequent occurrences of mighty tropical storms, accompanied by strong winds, abundant rainfalls and often causing the sea to surge into the cities. Hurricanes are areas of low pressure with a diameter of 300-500 km, accompanied by strong winds an d rainfalls, causing catastrophic effects to regions in their path.