After devastating Australia's east coast with an almost biblical level of flooding, La Nina has created ideal conditions for a dire bushfire season.

A report from Australasia's peak body for fire disaster management found the deluge of rain brought by La Nina helped boost grass growth in NSW and parts of Western Australia.

But as La Nina pares back and drier conditions come to the fore, the 2022 vegetation is expected to dry out over the first half of 2023, with below-average rainfall and normal to above-normal temperatures forecast.

This will leave behind swathes of long, spindly, dry grass that's perfect for combustion.

Even if conditions were to cool, the report warns dry, windy days would accelerate the flames.

The Australasian Fire and Emergency Service Authorities Council's bushfire specialist Simon Heemstra says the weather shift has elevated bushfire fuel loads and increased the risk of fast-spreading grass fires.

"Grass fires can move quickly and be deadly," Dr Heemstra said.

"We are seeing a shift in the climate drivers influencing Australia, which means our hazard risks are shifting too."

Fortunately regions recovering from the 2019/20 bushfires won't face the post-La Nina consequences other regions must confront.

The NSW south coast has below-normal fire potential because the excess rainfall from spring and summer has helped the charred bushland recover without accelerating vegetation growth.

The rest of the country shows normal fire potential, but Australians are being warned to remain vigilant.

"As we move out of the summer season, we urge communities to be mindful," Dr Heemstra said.