Monthly climate

Climate developments in December 2004

The South Pacific Convergence Zone (SPCZ), although not very active about and west of the Date Line, extended from the Solomon Islands east towards Samoa, including Tuvalu, Rotuma Island (northern Fiji), and Wallis and Futuna. Northern French Polynesia was also affected by the SPCZ, where it was more active than usual. Rainfall was well above average at Takaroa, in the Tuamotu Islands of French Polynesia, mainly because of high rainfall associated with tropical cyclone Judy in the third week of December. Rainfall was also above average in the Marquesas and Austral Islands, central and eastern Fiji, and northern New Zealand.

Three regions of suppressed convection with generally less than 50% of average rainfall occurred, one over Papua New Guinea, another over Samoa, the Southern Cook Islands, and central French Polynesia, and a third over Pitcairn Island. Rainfall was also below average over much of New Caledonia, Fiji’s Western Division and Southern Tonga.

Mean air temperatures were about 1.0°C above average in Fiji, and northern and southern French Polynesia, and about 0.5°C above average in Tuvalu, Samoa, and central French Polynesia, consistent with the warm sea surface temperatures (SSTs) affecting these regions. Mean air temperatures were near average in most parts of the region.

Tropical Southwest Pacific mean sea-level pressures continued above average about and west of the Date Line. They were below average in the east, especially over French Polynesia.

Climate extremes in December 2004