A Nowra rural property owner has been taken to hospital after fire swept through a farm and destroyed a shed on the town's outskirts.

Emergency warnings for bushfire burning 12km southwest of Nowra at Barringella Creek were downgraded on Friday evening, RFS commissioner Shane Fitzsimmons told ABC radio.

Residents in that area have been told to "watch and act".

RFS logistics officer Robyn Bolton told AAP that firefighters were concerned fire on the south side of Shoalhaven River around Yalwal Road could threaten properties along the river at Burrier and Coolendel.

She said five crews that had been patrolling a forest fire at Wandandian rushed off to lend a hand.

"They weren't able to get into a property that was in trouble," she said, before 80km winds came through from the south at 5pm (AEDT).

"There's certainly been a shed lost and the owner of the property was taken to hospital by ambulance."

Ms Bolton said if a westerly wind came through there was a danger the fire could jump the Shoalhaven River to the north side.

"If it crosses the river and we get a westerly switch it could sweep through a lot of residences," she said.