SES registration is from 7am with the search briefing starting at 8am.

Police asked for people to wear high visibility clothing for wet weather, sturdy footwear and bring plenty of water. 

The search will cover scrub near Benaroon Drive, including parts of the Kendall and Middle Brother state forests.

Weatherzone's Sam Brown said light coastal showers are likely from 8am, and these should taper off after lunch.

Fri 10.30pm: Police have changed the meeting place for tomorrow morning: People are asked to gather at Kendall Showgrounds from 7am on Saturday to join the search for William Tyrell. 

Weatherzone has predicted Friday night's patchy rain to continue on Saturday morning, as a trough brings showers to northeastern NSW. 

Fri, 7.45pm: Those wanting to help are asked to join the search on Saturday morning.

Searchers need to register with the SES from 7am at the end of Benaroon Drive, followed by a mandatory briefing at 8am.

Inspector Kerrie Brill said emergency services are working in dense bushland.

"The experts are out there now," she said.

"It's best to let them do what they do best, and any help would really be better in the morning." 

Inspector Brill said search numbers have been bolstered by Kendall residents returning home from work.

Fri, 6.10pm: Extra units from Taree have been sent to help with tonight's search, an SES spokesman said.

Surf Life Saving Clubs from up and down the Mid-North Coast are also sending their members to bolster numbers as it gets colder and darker out there.

Fri, 5.15pm: The darkness is closing in, but the searchers are not going anywhere.

Police Inspector Mick Aldridge said PolAir has returned to Sydney after extensive aerial searches.

"But we're not leaving - we'll continue all the way through the night," he said.

Inspector Aldridge said police officers, SES volunteers and concerned residents will search the area, which includes state forests, during the night and as morning begins.

PolAir may be called tomorrow morning, and the Westpac Rescue Helicopter Service may also be contacted for help. 

"We'll make those calls as the search goes on," Inspector Aldridge said.

Fri, 4pm: Horses and motorbikes are being used to comb the scrub around Kendall as the search for three-year-old William Tyrell.

Police said more and more people are arriving to assist in the search, with Inspector Mick Aldridge reporting a surge in numbers as schools and businesses close for the week.

There are now more than 40 concerned members of the community sweeping through the surrounding streets and areas, accompanied by about 30 SES personnel.

Twelve police officers continue to coordinate the search. 

Fri, 3.20pm: The search continues. PolAir are searching bushland surrounding Benaroon Drive, Kendall, from the air while emergency services and volunteers search on the ground.

Many in the community have joined the effort to find the missing three-year-old boy.

Our reporter on the scene says the terrain is very rugged and the search area is large. Several lines of people are searching the dense bushland, looking behind rocks and in drains. He estimates as many as 100 people are involved in the search. He has also joined one of the search lines.

"When you see the look on the faces of the family, you can't help but join the search and do what you can," he said.

The street leading up to the search area is packed with cars as people turn up to lend a hand. 

Dark clouds are also looming over the area.

Fri, 1.50pm: POLICE have established a mobile command outside the Kendall home of a missing three-year-old boy as the search for the toddler intensifies.

Emergency services in the area are scrambling to find the child, who was last seen about 10.30am on Friday in the front yard of his home in Benaroon Drive, Kendall.

He is described as having a Caucasian appearance, with dark hair and hazel eyes. He was last seen wearing a Spiderman costume.

More than 50 officers from the MNC Local Area Command, SES units from Port Macquarie, Wauchope and the Camden Haven, the Dog Squad and concerned residents have established a search grid in nearby scrub.

Police are grateful for offers of volunteer manpower but have asked the public to remain clear of the area so the search team can conduct a thorough sweep of the area.

PolAir is expected to arrive by 3pm.