The junior age titles were scheduled for Saturday, with the seniors, masters and surf boat carnivals to be held on Sunday at Thirroul.

However, Illawarra director of life saving Daren Weidner confirmed entries have reopened for the event, which will now be held next weekend.

"We had a meeting (on Thursday) morning and with the forecasts made the decision to push it back," he said.

"Entries will also now be open until Tuesday, so anyone who couldn't compete will have the opportunity next week.

"We also have the following week as a fallback, but hopefully the conditions will improve by next weekend."

READ MORE: Kembla Grange race meeting moved to Newcastle due to predicted heavy rain

A hazardous surf warning has been issued for the Illawarra on Thursday and Friday as the region braces for a deluge of rain.

The Bureau of Meteorology said surf and swell conditions are expected to be hazardous for coastal activities like rock fishing, boating and swimming.

As well as the Illawarra, the warning area covers the Sydney, Batemans Bay and Eden coast.

The NSW Police Force's marine command advised people to stay out of the water and avoid walking near surf-exposed areas.

The Illawarra could be in for more rain than it's received in almost three years with the bureau predicting rainfall of up to 100mm per day over the weekend.

If the maximum predicted rainfall occurs, the region would receive the highest monthly total since March 2017.

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