The dreaded southerly wind change has rapidly pushed the out-of-control Currowan fire north, creating another fire over the Kangaroo River just north of Nowra.

RFS units are in Kangaroo Valley and the Southern Highlands tonight working to save properties from the Morton Fire.

The strong winds caused the Currowan fire to cross the nearby Shoalhaven River this afternoon with the blaze later spotting into the valley and the highlands.

EMERGENCY WARNING – Morton Fire (Wingecarribbee LGA)

The fire is spreading quickly. If you are in Tallong, Werai, Exeter, Manchester Square, Avoca, Fitzroy Falls, Barrengary or surrounding areas it is too late to leave. Seek shelter as fire approaches. #nswrfs #nswfires #alert pic.twitter.com/ZzGIJk4Bu4 — NSW RFS (@NSWRFS) January 4, 2020 https://platform.twitter.com/widgets.js

EMERGENCY WARNING – Morton Fire (Wingecarribee LGA)

A fire is spreading quickly in the area N of Shoalhaven River. If you are in Bundanoon, Wingello, Penrose, Meryla and surrounding areas it is too late to leave. Seek shelter as the fire approaches. #nswfires #nswrfs #alert pic.twitter.com/2IxL7YNPKy — NSW RFS (@NSWRFS) January 4, 2020 https://platform.twitter.com/widgets.js

On the RFS radio transmission, firefighters spoke of houses alight at Wingello, a village in the Southern Highlands.

"Can we get more assets to Wingello," one firey said.

"We have multiple homes alight… if they don't come we're going to lose more."

The Currowan fire is moving quickly. Picture: RFS

The fire moved so rapidly the Southern Highlands RFS team was forced to quickly update their warnings for local residents.

"Predictions on fire spread after the Southerly change this evening indicate that the fire is unlikely to impact on any of the residential areas," the team wrote on Facebook just after 8pm.

Less than four hours later, at 10.45pm, the team was issuing an emergency warnings for residents in the same areas advising them to seek shelter.

Speaking to the ABC earlier, RFS Commissioner Shane Fitzsimmons said in the Shoalhaven region had been "burning aggressively".

"With so much fire, particularly the Currowan fire burning around Nowra and towards the southern end of the Southern Highlands and Kangaroo Valley and places like that, (the southerly) is going to continue to be heavily impacted by the effects of the southerly and whatever comes up along the ranges for many hours yet," he said.

"Lots of disparate fire grounds, lots of disparate areas that are impacting different communities, rural communities, isolated communities, towns and villages. It's going to be a long night ahead unfortunately not just for the firefighters and emergency services but all those people in and around those fire impact areas.

"Then as you head further south we have fires burning in the Shoalhaven on the coastal strip and those fires are burning very aggressively.

"We are now seeing not just the westerly and north-westerly influence driving those fires in and across the Shoalhaven towards Nowra and West Nowra areas but we're now seeing the southerly starting to move to the Shoalhaven, gusting up to 75km/h.

"We've got reports of that fire heading towards places like Kangaroo Valley, so we're very concerned about that fire at the moment."