Climate and Oceans Support Program in the Pacific (COSPPac) Bulletin

Issued 26 September 2025

• The El Niño Southern Oscillation (ENSO) remains neutral while a negative Ocean Dipole remain neutral.
• The Madden Julian Oscillation (MJO) is currently weak. Some international models forecast the MJO is likely to briefly strengthen in the Western Pacific before weakening as it moves to the Western Hemisphere and Africa.
• In August, the Intertropical Convergence Zone (ITCZ) was active and south of its normal position over the western Pacific over FSM and RMI. The South Pacific Convergence zone was active and shift south of its normal position over New Caledonia, Vanuatu, Fiji and southern Tonga.
• Sea surface temperatures (SSTs) for August 2025 were near normal to above normal in the central and western Pacific.
• The Coral bleaching alert on 23 September shows patches of 'Alert Level 1 and 2' over northern PNG and FSM.
• For September to November 2025, the models agree that above normal rainfall is likely or very likely over Palau, western FSM, western FSM, and a band stretching southeastwards over PNG, southern Solomon Islands, New Caledonia, Vanuatu, Fiji, Tonga, Niue, southern Cook Islands, and southern French Polynesia. Below normal rainfall is likely or very likely from northern FSM to northern RMI, and in a band stretching eastwards from northeast PNG, southeast FSM, Nauru to Kiribati (Gilbert, Phoenix, and southern Line Islands), Tuvalu, Tokelau, northern Cook Is., northern French Polynesia, and Pitcairn Islands.
• The weekly tropical cyclone forecasts from the ACCESS-S model shows significantly increased risks for Palau, FSM, Guam, CNMI, RMI, Philippines, south China sea region, and Japan for the 30 September to 06 October.