 On October 11, 1977, President Ernesto Geisel endorsed Law No.6448, which broke down Vilhena of Porto Velho, being recognized as a city of Rondônia since then.The climate is a transition between equatorial and tropical, hot and humid, with some short periods of cool weather from May to September, when the minimum temperature can reach 7 °C in the coolest days, but normally it stays around 12-16 °C.