Monthly climate

Climate developments in September 2004

The South Pacific Convergence Zone (SPCZ) extended from Papua New Guinea south-southeast to Rotuma Island. Convergence also occurred south of Fiji east to the Southern Cook Islands, including Tonga, some areas recording at least 200% of average rainfall. The enhanced rainfall over Papua New Guinea and the Solomon Islands was caused by cross-equatorial northerlies converging with the southern hemisphere trade winds. Enhanced convection and/or at least 125% of average rainfall also occurred in the far northern and southern islands of Fiji, Niue, the northern islands of Tuvalu, the Marquesas Islands, and Pitcairn Island.

Rainfall was 50% or less of average throughout much of Vanuatu, New Caledonia, the Tuamotu, Society and Austral Islands of French Polynesia, and Pitcairn Island. Rainfall was also less than 50% of average in several Northern and Central sites in Fiji.

Mean air temperatures were near average in New Caledonia, and more than 0.5°C above average in Samoa and the Society Islands of French Polynesia. Tropical Southwest Pacific mean sea-level pressures remained above average over Australia, and continued below average east of the Date Line.

Climate extremes in September 2004