Ribeira de Calhau is a settlement in the eastern part of the island of Sao Vicente, Cape Verde. It takes its name from the river Ribeira do Calhau, and comprises the villages Madeiral, Ribeira de Calhau and Calhau, all located near the river. 3 km south of Calhau is the extinct volcanic crater Viana. The Cape Verde Atmospheric Observatory "Humberto Duarte Fonseca" is situated 1 km north of Calhau.