A weak La Nina weather system has most likely reached its peak in recent weeks and is likely to end in autumn, according to the Bureau of Meteorology.

It says surface temperatures in the central tropical Pacific have warmed slightly since late December.

While atmospheric and sea surface indicators continue to reflect La Nina conditions, thresholds need to be exceeded for three months for 2017/18 to be classed a La Nina year.

Five of the eight climate models surveyed by the bureau suggest this will be the case, with the event lasting through the summer.

La Nina typically brings above-average rainfall to eastern Australia during summer, particularly in northern NSW and Queensland. However, a weak La Nina is typically less influential.

La Nina also increases the likelihood of prolonged warm spells for southeast Australia.