Insufficient rains in Southeast Asia, meanwhile, could dent supplies of palm oil, the world's most widely used vegetable oil, while extreme weather in top corn and soybean importer China is putting food output at risk.

The summer rainfall deficit could make essentials such as sugar, pulses, rice and vegetables more expensive and lift overall food inflation, which jumped in July to the highest since January 2020.

In an El Nino pattern, there is a higher chance of drier weather in Australia's east and it would likely be warmer than usual for the southern two-thirds of Australia.

The water services commission says most of the dams in the country have water levels of above 90%.

The monsoon is the lifeblood of the country's US$3 trillion economy, Asia's third-largest, and delivers nearly 70% of the rain it needs to water farms and recharge reservoirs and aquifers.