Island Climate Update 262 - July 2022

04 July 2022

The NINO3.4 Index anomaly (in the central equatorial Pacific) over the last month was -0.40˚C, in the “cool-neutral range”. The three-monthly NINO3.4 Index remained near the La Niña threshold. The June monthly SOI was +2.1, which continues to strongly signal La Niña.

Jul-Sep 2022 Island Climate Update

Watch Video

In the subsurface equatorial Pacific, warmer than average water (+1˚C to +3˚C) was nearing the surface in the east at the end of June. Upper oceanic heat content increased in the central Pacific but remained below average in the east. Overall, this indicated a weakening of La Niña.

Trade winds across the equatorial Pacific were weaker than normal in the North Pacific and slightly stronger than normal in the South Pacific. This was associated with warming SSTs near and north of the equator. A surge in trade winds establishing during the first half of July may halt or reverse the recent warming trend and could result in a cooling of the equatorial Pacific sub-surface and surface over the next three months.

La Niña conditions are most likely to continue during July-September (60% chance). During October-December, there is a 60% chance for La Niña and a 35% chance for ENSO neutral. During January-March, there is around a 40% chance for La Niña and a 50% chance for ENSO neutral.

A pulse of tropical convection looks to move over the region in early in July and then into the western Pacific by mid-July, bringing rainfall to areas including Vanuatu, New Caledonia, Fiji and Tonga.