The chances of an El Nino weather system this year cannot be ruled out despite the likelihood easing in some models, the Bureau of Meteorology says.

The bureau’s outlook remains at “El Nino watch”, meaning there is a 50% chance of the system developing this year.

Sea surface temperatures in the tropical Pacific Ocean have warmed since the start of the year, but remain below El Nino thresholds.

“Some international climate models have reduced the likelihood of El Nino this year compared to last month,” the bureau says.

“However, five of eight international climate models still indicate the tropical Pacific Ocean may exceed El Nino thresholds during the second half.”

The crucial Indian Ocean Dipole (IOD) remains neutral, but four out of six climate models suggest a positive IOD is likely to develop during this winter.

El Nino usually brings drier than average winter and spring conditions in eastern Australia, and if it combines with a positive IOD then the effect is exaggerated.

An increase in bushfire weather is likely, but the number of tropical cyclones tends to reduce in El Nino years.