BOM: La Niña likely to continue through summer 2020−21
Most models suggest the La Niña will strengthen, peaking in December. Around half the models anticipate a strong event, meaning there is a possibility it could reach similar strength to the La Niña of 2010–12. However, models forecast this event will be shorter, possibly ending in the first quarter of 2021. The strength of La Niña impacts on Australia are often related to the strength of the event.
Central and eastern tropical Pacific Ocean sea surface temperatures remain around La Niña thresholds (0.8 °C below average) and atmospheric indicators, including the Southern Oscillation Index (SOI), trade winds and cloud, are also at La Niña levels.
La Niña typically increases the chance of above average rainfall across much of Australia during spring. Above average summer rainfall is also typical across eastern Australia. Current climate outlooks indicate November 2020 to January 2021 will be wetter than average for much of the country.
In the Indian Ocean, there has been significant warming of sea surface temperatures in the west of the Basin over the past fortnight. Models have reduced the likelihood of a negative IOD event in 2020, noting that the IOD typically breaks down in late spring or early summer.
