Police are searching dams and tanks for a four-year-old boy who went missing on his remote homestead over 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.

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 will search dams and tanks on the property while officers on horses search the property.

SA Police Senior Constable Matt Hale told ABC Radio Adelaide that they were still “hopeful for a good outcome” but stressed that “time is of the essence”.

“This is his backyard, so it’d be quite easy for kids to be comfortable in that environment, but also easy for them to get lost,” he said.

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.

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