Emergency warnings issued for NSW fires

Two bushfires are threatening homes in northern NSW, and the Rural Fire Service (RFS) has mobilised at least 15 trucks and an aircraft to battle the blazes.

An emergency warning has been issued for a five-hectare bushfire at Yamba in the state's northeast.

At least 10 trucks are being used to bring it under control, and the RFS has warned the fire is approaching the Yamba Waters Caravan Park.

It was unclear how many homes were under threat, an RFS spokesman told AAP on Saturday afternoon.

Further south at Kremnos, crews are protecting properties from a smaller out-of-control fire.

"They are seeing some windy conditions up there at the moment," the spokesman said.

"At Kremnos there would be more than five trucks plus an aircraft working that one."

Strong winds are expected to continue through Saturday afternoon, but the RFS is hoping for cooler conditions on Sunday.

"The message for people in both those areas is to seek shelter as the fire approaches," the spokesman said.

Earlier on Saturday, police arrested a 16-year-old boy who is accused of deliberately lighting a fire that burnt through scrubland and came close to a shopping centre and homes near Killarney Vale on the Central Coast.

Elsewhere, watch-and-act alerts have been issued for an out-of-control blaze that has burnt through a hectare of bush north of Grafton and two small grassfires south of the town.