The Bureau of Meteorology says El Nino has ended and Pacific Ocean conditions have returned to neutral, and it has urged caution around predictions of La Nina – associated with increased flood risk – developing later this year. 

International models suggest conditions are likely to remain neutral until at least July, while three out of seven predict central Pacific sea surface temperatures will probably then reach La Nina thresholds.

The bureau says forecasts for the El Nino Southern Oscillation (ENSO), which describes swings between the opposite climate drivers, vary in accuracy depending on timing, and past indicators may not be an ideal guide.

“El Nino and La Nina predictions made in mid-autumn tend to have lower accuracy than predictions made at other times of the year,” it says.

“This means that current forecasts of the ENSO state beyond July should be used with caution.”

Global sea surface temperatures have been the warmest on record for each month between April last year and March, and this month are on track to be warmer than a year earlier.

“The global pattern of warmth is affecting the typical historical global pattern of sea surface temperatures associated with ENSO variability,” the bureau says.

“As the current global ocean conditions have not been observed before, inferences of how ENSO may develop in 2024 that are based on past events may not be reliable.”

La Nina events are normally associated with above average winter, spring and early summer rainfall over much of Australia, and an increased risk of flooding. El Nino is more associated with dry weather and conditions favouring bushfires.