Matoury Rainfall At Matoury in French Guiana, for a period of record spanning 1971 – 2014 average annual rainfall sum = 3581 mm wettest year on record = 5137.2 mm of rainfall in 1976 driest year on record = 2270.3 mm of rainfall in 1995 wettest month on average = 577.8 mm of rainfall in May …