A spokeswoman for the Maritime Safety Bureau said the 12.9-metre yacht, with two people aboard, was last heard from on August 27 when it was just 40 nautical miles east of the Seaway Tower off Southport in Queensland.

The crew indicated their intention to make land between Southport and Newcastle.

Searchers are keeping on eye on the weather and expect a break mid-morning to allow a search to begin.

Five State Emergency Service air observers will join the search, in waters from Moreton Bay to Newcastle and 50-60 nautical miles out to sea.