Eastern Australia is expected to receive above average rainfall in the fourth quarter of the year, with increased flood risk in parts of NSW and Queensland.

Climate influences driving the Bureau of Meteorology outlook include sea surface temperatures west of Australia, reflected in the Indian Ocean Dipole index.

“A negative Indian Ocean Dipole is likely to persist until early summer, likely contributing to above average rainfall in eastern Australia, the bureau says.

“For eastern NSW and southeast Queensland where soils are wetter than average, this forecast indicates an increased flood risk in the coming months.”

Many east NSW sites monitored by the bureau recorded their wettest August on record, but rainfall deficiencies persist in parts of the nation’s southeast, especially Tasmania.

The criteria for a negative dipole are met when temperatures are less than or equal to a threshold level for eight consecutive weeks.

An update last week showed the threshold had been met for seven weeks, with a strong forecast for conditions to continue.

The El Nino-Southern Oscillation, which reflects conditions in the Pacific, remains neutral.

“The bureau’s model predicts some further cooling of the tropical Pacific is likely, potentially reaching La Nina levels briefly during spring, and returning to neutral in the austral summer,” the update says.

About half of the international models assessed by the bureau indicate neutral conditions will prevail, and the other half indicate a La Nina, associated with wetter weather in eastern Australia, may develop.

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