Continued cooling in the tropical Pacific Ocean, means the prospect of a La Nina later this year has increased.

The increase in rain and cloudiness in the western Pacific associated with La Nina usually means above-average winter-spring rainfall for Australia, particularly across the east and north

The Top End has had a run of poor wet seasons the last two years.

The bureau says the majority of computer prediction models anticipate this cooling will be close to the threshold for La Nina by early spring.

The bureau has shifted its outlook to La Nina watch.

This means the chance of La Nina forming in 2020 is around 50%-roughly double the average likelihood.

Three models indicate a La Nina could form by late winter, with another two models suggesting thresholds could be approached during early spring.

"La Nina events typically bring above average spring rainfall in northern, central, and eastern Australia," the bureau said.

"Key indicators of ENSO, such as the Southern Oscillation Index (SOI), trade winds, cloudiness near the Date Line, and sea surface temperatures in the tropical Pacific Ocean, are consistent with a neutral ENSO state.

"However, sea surface temperatures across the tropical Pacific Ocean have cooled over the past two months, and are supported by temperatures below the surface of the tropical Pacific Ocean, which are also cooler than average."

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