La Niña is favored to continue through Northern Hemisphere winter 2022-23, with a 91% chance in September-November, decreasing to a 54% chance in January-March 2023.
During August, below-average sea surface temperatures (SSTs) persisted across the central and east-central equatorial Pacific Ocean [Fig. 1]. The largest SST anomalies were evident in the Niño-3.4 and Niño-4 regions, with the latest weekly values reaching -0.8°C and -1.1°C, respectively [Fig. 2]. Negative subsurface temperature anomalies were mostly unchanged during the month [Fig. 3], reflecting the dominance of below-average temperatures across the eastern Pacific Ocean [Fig. 4]. Low-level easterly wind anomalies and upper-level westerly wind anomalies continued across most of the equatorial Pacific. Convection and rainfall remained suppressed over the western and central tropical Pacific and enhanced over Indonesia [Fig. 5]. Overall, the coupled ocean-atmosphere system continued to reflect La Niña.
The most recent IRI plume forecast of the Niño-3.4 SST index indicates La Niña will persist into the Northern Hemisphere winter 2022-23 [Fig. 6]. There is an interesting split in the dynamical versus statistical model forecasts, with the latter set suggesting La Niña will persist longer, through January-March 2023. At this time, the forecaster consensus sides with the statistical models, although there is still large uncertainty over how long La Niña will last and when it will transition to ENSO-neutral (56% chance of a transition to ENSO-neutral during February-April 2023). In summary, La Niña is favored to continue through Northern Hemisphere winter 2022-23, with a 91% chance in September-November, decreasing to a 54% chance in January-March 2023 [Fig. 7].