Indian Ocean temperature patterns may worsen any southern Australian rainfall shortages caused by an El Nino climate event this year.

The Bureau of Meteorology says there is a 50% chance an El Nino will form, while three of six models suggest a short-lived positive Indian Ocean Dipole (IOD) may develop.

“The ocean to the northwest of Australia remains cooler than normal, which is contributing to suppressed rainfall over southern and southeast Australia,” the bureau says.

“A positive IOD during spring typically reduces rainfall in central and southern Australia, and can exacerbate any El Nino-driven rainfall deficiencies.”

An El Nino is caused by Pacific Ocean temperature and atmosphere changes, and typically brings warmer temperatures, reduced rainfall and increased fire danger in southeast Australia.

Most international climate models surveyed by the bureau predict warming of the tropical Pacific is likely to restart in coming weeks, with potential for El Nino thresholds to be met by mid to late spring.

A positive Indian Ocean Dipole occurs when there are warmer surface temperatures in the west than the east.