A statement on Tuesday said the weather and climate agency was now predicting a 50 per cent chance of La Nina forming - which was about twice the usual likelihood.

The BoM said three of the seven models it used predicted La Nina, while two others "briefly touch" the threshold.

"La Nina events increase the chances of above-average rainfall for northern and eastern Australia during spring and summer," the BoM said.

It comes after a wetter-than-average summer in NSW in 2020-21.

Last storm season, which typically goes from October to March, ended with rain and flooding battering much of the state - with the Hunter copping its share of deluge and damage, particularly in the Port Stephens area.

Hunter State Emergency Service spokesperson Alex Varley said the SES understood that rainfall for much of NSW was likely to be above the average median from October to December.

"Our volunteers are ready to respond to all requests for assistance," she said.

The COVID-19 lockdown has meant training for SES personnel has moved online and most units have put a temporary hold on recruitment until face-to-face contact resumes, Ms Varley said.

"However, NSW SES units across the Hunter are still responding to operational needs and member numbers in those units are strong," she said.

"Units have adapted and changed some of the ways they do things to keep themselves and their communities safe and comply with the current Public Health Order.

"At this time, units will continue their current training and maintenance and will adjust their operational readiness needs as the season progresses. Unit leadership teams are in regular communication with the [SES regional] zone and BoM and are ready to adjust their approach as needed."

The SES is urging people to prepare for storm season, with Commissioner Carlene York saying NSW was likely to experience similar conditions to last storm season - which could include flash-flooding and heavy rain.

"The more you can do now to prepare, the less likely you'll end up needing emergency assistance from our volunteers when these weather events hit," Commissioner York said.

"Our website has everything you could possibly need to learn about your risk of floods and the dangers they bring.

"It also highlights the simple, yet effective, things you can do ahead of time.

"From preparing an emergency evacuation kit, making sure your gutters and downpipes are clear, to planning for your animals, you can find all this information and more via ses.nsw.gov.au."

IN THE NEWS:

Our journalists work hard to provide local, up-to-date news to the community. This is how you can continue to access our trusted content: