The possibility of an El Nino weather effect developing this year is reducing, but the chances of a positive Indian Ocean Dipole (IOD) are rising.

Both weather phenomena typically bring below average rainfall for southern, eastern and central Australia.

The Bureau of Meteorology says climate models “suggest some easing” for the chance of El Nino– but half of the surveyed models “still indicate an event is possible”.

As a result an El Nino watch remains in place, meaning the chance of El Nino this year remains about 50% – double the normal likelihood.

The IOD index has exceeded the positive threshold in the last fortnight, but the bureau says it will take “several more weeks of similar values before a positive IOD event is considered established”.