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Island Climate Update 258 - March 2022

The NINO3.4 Index anomaly (in the central Pacific) during February was -0.60˚C, near the La Niña threshold. The monthly Southern Oscillation Index (SOI) was +0.7 and the three-month average SOI was +0.8, the latter near the La Niña threshold.

Upper-oceanic heat content increased in the western and central Pacific for the second consecutive month. For the first time since June 2021, conditions in the upper 300 meters of the equatorial Pacific were generally warmer than average, signalling that the La Niña event is nearing its end.

In the subsurface equatorial Pacific, a warm pool of water continued to push eastward and progressed closer to the surface. This will likely spell the end of oceanic La Niña conditions by May.

La Niña conditions will likely give way to ENSO neutral conditions between April-June (60% chance). Between June-August, ENSO neutral is favoured at a 60% chance. ENSO neutral is also favoured from September-November (45% chance).

Suppressed convection over the western Pacific during the first half of March will reduce the risk for tropical cyclone activity. There may be an increased risk for cyclone development later in the month, particularly in the western part of the basin near New Caledonia and Vanuatu. The cyclone season runs through April. So far, five tropical cyclones have formed.