The mean annual temperature ranges between 24 and 26° C (75 and 79° F) along the northern section of the coastal plains, from 22 to 24° C (72 to 75° F) towards more elevated zones in the south, and from 20 to 22o C (68 to 72° F) in the highest zones of the province, like the Sierra de Nipe. The fluctuations of average annual rainfall progressively increase from plain zones around urban areas to mountainous and wood areas in the center of the province. Thus, the annual average ranges from 600-800 mm (24-31 in), in littoral and sub-littoral plains, reaching 1800-2000 mm (71-79 in) in the mountains of Nipe and Cristal. In normal years, the rainy season starts in the first third of April towards the lower-mountain areas. This peculiarity takes place in other eastern orographic groups and in the mountains of Guamuhaya, in central Cuba. In such cases the duration of the rainy season is about 200-day longer than in coastal plains and low zones of the rest of the island.