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

Issued 09 September 2026

• The El Niño is firmly established.
• A moderate Madden-Julian Oscillation (MJO) signal is currently located in the Western Hemisphere with forecasts to continue active in the Western Pacific during early August.
• In August, the Intertropical Convergence Zone (ITCZ) was active along its climatological position and shifted south in the eastern Pacific. The South Pacific Convergence zone (SPCZ) was active and enhanced further east northeastwards of its climatological position towards Kiribati Line Islands.
• Sea surface temperatures (SSTs) for August 2026 were mostly near normal to above normal across the Pacific, with highest-on-record values along the equatorial central to eastern Pacific, especially around Kiribati, northern Tokelau, the northern Cook Islands and northern French Polynesia.
• The Coral bleaching risk remains highest along the equator over Kiribati, with Alert Level 2 conditions expected to persist to 21 September 2026 and lower-level watch or warning conditions extending to nearby northern Pacific areas.
• For September to November 2026, the models agree that above normal rainfall is likely or very likely over eastern FSM, northern and southern RMI, Nauru, Kiribati (Gilbert, Phoenix, and northern Line Is.,), northern Tuvalu, Tokelau, northern Cook Islands, and far northern French Polynesia. Below normal rainfall is likely or very likely for CNMI, Guam, Palau, PNG, Solomon Islands, New Caledonia, Vanuatu, Fiji, Tonga, Niue, southern Tuvalu, Wallis and Futuna, Samoa, American Samoa, southern Tokelau, most of Cook Is., most of French Polynesia, and Pitcairn Islands.
• The The weekly tropical cyclone forecasts from the ACCESS-S model shows increased risks in the north-western Pacific near near Guam, CNMI, Palau, FSM, and RMI for the week of 13-26 September 2026.