Crews will persist in their search throughout the night for a four-year-old boy who disappeared from his isolated homestead approximately 235km north-east of Adelaide during the weekend.

August, or Gus, was last seen on a property in mid-north South Australia, about 40km south of Yunta, at 5pm on Saturday.

He was reportedly playing in his grandparents sandpit at this outback homestead.

Local officers searched the area with a helicopter and an infra-red camera that same night, but were unable to find him.

Crews have used trail bikes, ATVs, horses and a drone and a helicopter to scour a 2.5km radius from where Gus was last seen.

Today, police attached to water operations searched dams and tanks on the property while officers on horses searched the property.

“As demonstrated by the vastness of the property here, it’s extensive. That’s why we have allocated as many resources as possible to locate young Gus,” explained Superintendent Mark Syrus.

“This poor lad just four years old and very close to the family so they’re devastated.”

Gus is described as Caucasian with long, blonde, curly hair.

He was wearing a grey sun hat, a cobalt blue t-shirt with a yellow minion from the movie Despicable Me on the front, light grey long pants and boots.

His family have declined to release an image of him.

It is believed to have gotten down to six degrees in the two nights he has been missing

“It would be uncomfortable for him but don’t anticipate those sub-zero temperatures which is quite common up here,” Syrus said.

Anyone who sees a boy matching his description or has information is urged to contact Crime Stoppers.