Monthly climate

Climate developments in January 2005

Unlike in December 2004, the South Pacific Convergence Zone (SPCZ) was quite active west of the Date Line, extending from Papua New Guinea east toward Tokelau. This was linked to a large region of enhanced convergence, which also affected the Caroline Islands, the Solomon Islands, and Vanuatu. Enhanced convergence also affected New Caledonia, with generally well above average rainfall there, some places recording more than 600 mm (mainly from the passage of tropical cyclone Kerry near Chesterfield Island to the west over 8-13 January). Rainfall was well above average in parts of Fiji’s Northern Division, and also in the Marquesas Islands of northern French Polynesia. Udu Point, in Fiji, measured rainfall totalling 160 mm on 28 January.

A large region of suppressed convection covered much of Indonesia and Australia. In the Pacific, regions of suppressed convection and mostly 50% below average rainfall occurred over Eastern Kiribati and parts of central and southern French Polynesia, with another, although less anomalous, area of suppressed convection over the region between Samoa, Fiji, and Tonga. Fiji’s rainfall was below average, apart from some areas in the northeast.

It was warmer than usual throughout much of the Southwest Pacific in January, with mean air temperatures 1.0 °C or more above average on many islands, and about 0.5 °C above average in Vanuatu, Fiji, and the Marquesas Islands. A heatwave occurred from 4-7 January in La Tontouta, New Caledonia, with maximum temperatures between 36 and 37 °C. New Caledonia’s mean temperatures were 1.3 °C above normal for the month.

Tropical Southwest Pacific mean sea-level pressures continued above average well west of the Date Line. They were below average about and east of the Solomon Islands and further east, especially near the equator. Equatorial easterlies along the equator were stronger in January 2005 than in most recent months.

Climate extremes in January 2005

Outgoing Long-wave Radiation (OLR) anomalies, in Wm-2 are represented by shaded areas. High radiation levels (yellow) are typically associated with clearer skies and lower rainfall, while cloudy conditions lower the OLR (blue) and typically mean higher rainfalls. The January 2005 position of the South Pacific Convergence Zone (SPCZ), as identified from total rainfall, is indicated by the solid green line. The average position of the SPCZ is identified by the dashed green line. Data source: NOAA-CIRES Climate Diagnostics Center.