Successive postponements were announced throughout the day at Royal Brighton Yacht Club, before the decision to abandon was made at 3pm local time.

Two races had been scheduled and organisers in Australia are now hoping to hold three tomorrow.

Sailors waiting to see if racing was possible had to do so in extreme heat, with temperatures climbing north of 40 degrees.

Many opted to go swimming to cool off.

"Faced with challenging forecast winds on a hot Melbourne day, pressure never eventuated, and the Race Committee was forced to cancel all racing for the day, with little likelihood of any better conditions during normal sailing times this evening," principal race officer Mark Taylor said. 

"The forecast is looking more positive [tomorrow] and sufficiently positive to not bring forward the start time, but hopefully to get three races in a southerly breeze, currently forecast at 10 to 15 knots."

New Zealand's Josh Junior is the current leader of the event after four races over the first two days.

He has a 14-point advantage over Croatia's Nenad Bugarin.

The event has greater significance for Oceania athletes, with competition acting as the continent's qualifier for next year's Olympic Games in Tokyo.

For countries such as Canada, New Zealand and the United States, who have already secured a spot at Tokyo 2020, the competition is serving as an Olympic selection event.