THE Bureau of Meteorology has doubled down on its predictions of a wet summer, saying La Nina conditions in the tropical Pacific are set to persist through summer.
According to BOM most weather prediction models suggest the La Nina 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 Nina of 2010-12," BOM says in a statement issued on Tuesday.
"However, models forecast this event will be shorter, possibly ending in the first quarter of 2021.
"The strength of La Nina impacts on Australia are often related to the strength of the event."
BOM says central and eastern tropical Pacific Ocean sea surface temperatures remain around La Nina thresholds (0.8 degrees Celsius below average) and atmospheric indicators, including the Southern Oscillation Index, trade winds and cloud, are also at La Nina levels.
"La Nina typically increases the chance of above average rainfall across much of Australia during spring," BOM says.
"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.
The Southern Annular Mode is expected to be positive for the remainder of October. La Nia tends to favour positive SAM during spring and summer, further enhancing the wet signal in the east.
The Madden-Julian Oscillation is in South East Asia's maritime continent and is expected to increase in strength as it moves into the western Pacific Ocean.
BOM says climate change is also influencing Australia's climate.
"Australia's climate has warmed by around 1.4 deg C since 1910, while southern Australia has seen a 10-20pc reduction in cool season (April-October) rainfall in recent decades," BOM says.