The Forum will concentrate on the theme of climate change in preparation for the World Climate Summit in Paris at the end of November.
Leaders are attending from Nauru, Kiribati, Federated States of Micronesia, Solomon Islands, Tonga, Tokelau and Tuvalu.
Marshall Islands is sending its Foreign Minister.
Thailand's prime minister is not now attending as the Forum's chief guest and the country will instead be represented by the deputy prime minister General Tanasak Patimapragorn.