La Nina expected to run for three months, or even longer

Mr Grey compares 12 climate models, from different forecasting organisations throughout the world, every month.

"Everyone is predicting the La Nina will hang around for six months at least and that is highly believable," Mr Grey told the latest AgVic climate webinar.

"In July, La Nina was dead and buried, it was gone for all money."

Since then, a significant pool of cool water had developed off the coast of Chile.

"There is so much cold water, around the Pacific, it won't disappear in four weeks time," he said.

While most models had been confidently predicting a La Nina all year, he said he wasn't so sure.

"But we've seen the cloud patterns, the pressure patterns, all singing from those wetter hymn sheets,' Mr Grey said.

"I think my confidence is slowly improving."

The Pacific Ocean trade winds had been "really cranking" and conditions for a La Nina holding and progressing were evident in more than half of that sector.

Cloud patterns had been strange all year, as they were not remotely like those in a La Nina, he said.

But there had been a build up of cloud to the north of Australia, which was more conducive to a La Nina.

"It's a late burn, with what is going on there," Mr Grey said.

"The pressure patterns around the Equator have also been singing from the same La Nina hymn sheet.

"We might come home with a wet sail, but we will be really hoping the tap turns off, we really only want a wet October."

He said he was hoping rainfall in November and December would not be as heavy.

"We can then get those headers going into what, in south-east Australia, is going to be a pretty strong harvest," he said.