The climate is characterized by hot days and cool nights. There are two clearly defined seasons, a rainy season from March to June, and a dry season for the remaining months. The interior of the state is covered mostly by the dry thorny scrub vegetation called "caatinga". The Rio São Francisco is the main water source for this area. The climate is more mild in the countryside of the state because of the Borborema Plateau ("Planalto da Borborema", popularly known as "Serra das Russas" or "Russians' Mountain"). Some towns are located more than 1000 meters above sea level, and temperatures there can descend to 10 °C (50 °F) and even 5 °C (41 °F) in some cities (i.e., Triunfo) during the winter. The island of Fernando de Noronha in the Atlantic Ocean, 535 km northeast of Recife, has been part of Pernambuco since 1988. The rivers of the state include a number of small plateau streams flowing southward to the São Francisco River, and several large streams in the eastern part flowing eastward to the Atlantic. The former are the Moxotó, Ema, Pajeú, Terra Nova, Brigida, Boa Vista and Pontai, and are dry channels the greater part of the year. The largest of the coastal rivers are the Goiana River, which is formed by the confluence of the Tracunhaem and Capibaribe-mirim, and drains a rich agricultural region in the north-east part of the state; the Capibaribe, which has its source in the Serra de Jacarara and flows eastward to the Atlantic at Recife with a course of nearly ; the Ipojuca, which rises in the Serra de Aldeia Velha and reaches the coast south of Recife; the Serinhaen; and the Uná. A large tributary of the Uná, the Rio Jacuhipe, forms part of the boundary line with Alagoas. Originally inhabited by numerous tribes of Tupi-Guarani speaking indigenous peoples, Pernambuco was first settled by the Portuguese in the 16th century. The French under Bertrand d'Ornesan tried to establish a French trading post at Pernambuco in 1531. Shortly after King John III of Portugal created the Hereditary Captaincies in 1534, Pernambuco was granted to Duarte Coelho, who arrived in "Nova Lusitânia" (or "New Lusitania") in 1535.