The climate of New Caledonia
Luc Maitrepierre, Meteo-France, New Caledonia
New Caledonia is a tropical archipelago located between latitude 18°S and the tropic of Capricorn, and between longitudes 164° E and 168° E. The total land area is approximately 19,000 km� with 16,900 km� for the main island “Grande Terre”. Grande Terre is dominated by an almost continuous mountain range from northwest to southeast. The average altitude of the range is 1000 m with two peaks above 1600 m: Mt Panié in the north and Mt Humbolt in the south. The interaction between the topography and east to southeasterly tradewinds impacts on the annual rainfall distribution. On the west coast the average annual amount is 800 mm to 1200 mm while on the east coast it is 1750 mm to 4000 mm. New Caledonia is often affected by climatic hazards such as tropical cyclones, floods and droughts.
The El Niño Southern Oscillation (ENSO) also plays an important role on rainfall and cyclone activity. For the geographical domain around the archipelago (18°S to 24°S and 162°E to 170°E), research shows that there is usually increased cyclonic activity (+32%) during La Niña events whereas there are usually the normal frequencies of tropical cyclones during the El Niño events. El Niño episodes tend to reduce rainfall, which sometimes causes severe droughts especially on the west coast. Above average rainfall is usually experienced during La Niña events, which impact on agriculture and mining (Figure 1).
There are two main seasons, the wet season (December to March) and the dry season (mid July to November) (Figure 2). During the wet season, rainfall tends to be higher in the northern part of the main island. For example, at Nouméa, the monthly rainfall is lower than that recorded at Koumac for January and February but higher from April to August for a very similar annual amount. There are also large differences in rainfall amounts between the two coasts such as between Poindimié located on the east coast of the main island and stations located on the west coast (Koumac and Nouméa).The average temperature is about 23°C with an annual variation of 6°C to 8°C between the warm and cool season. Minimum temperatures can sometimes be very low in some places: overnight temperatures below 10°C are not unusual inland and the extreme minimum is 2.3°C. The extreme maximum temperature ever recorded is 38.8°C at Poya. The diurnal temperature range is very dependent on the location: areas closer to the sea have a smaller diurnal temperature range.
Over the last 40 years, temperatures in New Caledonia have increased by about 0.8 °C, the increase being particularly noticeable over the last 25 years. Furthermore, there is a very strong correlation between temperature anomalies in New Caledonia and the ENSO phenomenon. During El Niño events, temperatures are cooler than normal, whereas they are warmer than normal in La Niña phases with a maximum range of +0.8°C.
