Police and emergency services resumed the search on Friday morning for Natalya Franklin, 9, who vanished from her family's rural property in the small town of Raleigh, about 25 kilometres south of Coffs Harbour, on Thursday morning.

Police said Natalya had an argument with two of her sisters at the family's home on North Bank Road about 10.30am, after which Natalya went to her bedroom and closed the door.

When her parents went to check on her about 12.30pm, Natalya was not in the room and the window was open. Her parents called police immediately and officers searched the property and surrounding areas, but could not find any trace of her.

Superintendent Mark Holahan said Natalya and her siblings were home-schooled, and her disappearance was "extremely out of character".

"Their [the family's] life revolves around their home and their church, with the occasional visit to Bellingen to do shopping or go to the library," Superintendent Holahan told the ABC.

"She was very upset about the fight with her sisters.

"There was a lot of activity around the house [during the search on Thursday afternoon], we're hoping that she saw all that and was a bit fearful of coming home."

At the time of her disappearance, Natalya was wearing bright pink shorts and a peach-coloured T-shirt. She was not wearing any shoes.

The temperature dipped to 8.2 degrees in Coffs Harbour overnight, but taking into account the wind chill factor, it felt more like five degrees, according to the Bureau of Meteorology.

Police from the Coffs-Clarence Local Area Command and State Emergency Service volunteers searched the family's home on Thursday afternoon.

When they could not immediately find Natalya, they called in the police Dog Squad and officers from the Marine Area Command to search the Bellinger River, which flooded during recent heavy rain. The family's property is within several hundred metres of the river.

The search, involving about 50 people, resumed on Friday morning, with the police helicopter and police divers also joining in.

Natalya's father, Brett, and friends were organising for trail bike riders to search the nearby Bongil Bongil National Park for any sign of his daughter on Friday.

Natalya's family are involved with Coffs Harbour's Lifehouse Church, which has appealed for people to pray for Natalya's safe return.

Police say they do not believe there is any link between Natalya's disappearance and an incident in which two boys were approached by a stranger in Corindi Beach, about 35 kilometres north of Coffs Harbour, on Wednesday morning.

The boys were riding their bikes to school along Matthews Parade when a light coloured Holden Commodore pulled up behind them. A female passenger got out of the car and attempted to speak to the boys, who rode away and alerted a school teacher, police said.

"We don't believe there is any link between the two cases at this stage," a NSW Police spokesman said.

Natalya is described as having a fair complexion, with long, light brown hair. She is about 145 centimetres tall with a thin build.

Anyone with information about Natalya's disappearance has been urged to call Crime Stoppers on 1800 333 000.