Beachgoers got more than they bargained for while escaping the hot weather at Warilla Beach when a scrub fire started at the northern end on Sunday.
Emergency services were called to the scrub fire in the nature strip between Warilla Beach and Osborne Parade around 3.20pm, just metres from parked cars and beachgoers.
Three fire trucks from Fire and Rescue NSW were on scene and four units from the Rural Fire Service, with around five acre of nature strip alight.
A man in his 70s was treated for heatstroke at the scene by paramedics, NSW Ambulance confirmed.
As of 4.20pm authorities said they had the upper hand on the blaze, though its cause was still unknown.
"There's no exposures, there's nothing under threat. There's a little bit of wind down there from the west and they're just working to knock it out," Superintendent Adam Dewberry said.
About 8pm, fire crews returned to the site to extinguish a small re-ignition of the scrub fire that flared up after the southerly change came through.
It's not the only bushfire on the hot day with a small blaze erupting at Kiarama Ave in Kiama Downs around 2pm, but firies were able to extinguish that quickly - only burning around 10 square metre of scrub.
It was a scorcher of a Sunday for the Illawarra with hot, gusty west-northwesterly winds exacerbating what was already a 35 degree day for Albion Park and Wollongong, and 34 for Kiama.
It is unusual spring weather for the region, with the mean temperatures for October across the Illawarra sitting in the low 20s.
Officers attached to Lake Illawarra Police District established a crime scene and commenced an investigation into the circumstances surrounding the fire which burnt five acres of scrub.
"As inquiries continue, anyone with information about this incident is urged to contact Lake Illawarra Police District or Crime Stoppers on 1800 333 000," a NSW Police spokesperson said.
Sign up for our newsletter to stay up to date.