Residents were on high alert as they waited to see if any fires ignited during the 'catastrophic' danger risk declared for the day.

Many children who were given the day off school due to the fire threat were at beaches, pools or at home in air-conditioning.

Read more: Police investigate two 'deliberately lit' fires in Wollongong

Margaret Luck was looking after her grandchildren while their mother was at work and took them to Helensburgh swimming pool to cool off and have some fun.

"The children think it's exciting to be off school," she said.

"We were here when the 2001 fires were in the area and they came right up to our door which was distressing.

"We are keeping our fingers crossed and thinking of all the people up north who are in trouble.

"We are packed and are ready to go. I live at Austinmer so the family will come to me if any fires happen in Helensburgh."

By mid afternoon a brown haze settled over the Illawarra, reducing visibility, brought on by the westerly wind and not compounded by a late southerly change.

Many people were still enjoying the last of the hot temperatures at the Fairy Meadow Beach in the afternoon.

There was a top temperature of 36 degrees Celsuis but dropped to 18 by 7pm. The air quality was 'poor'.