A rainbow fills the sky after heavy rains hit Cobar, Australia, 442 miles (712 kilometers) northwest of Sydney on May 17, 2007.

Rainstorms in parts of the Australian state of New South Wales in April and May gave hope to farmers that the drought was breaking. But the optimism was short-lived as farmers struggled through a hot and dry winter.

No one knows what will break the drought cycle. La Niña conditions that usually promote rainfall are dissipating, and climatologists say it is too soon to know what will follow. Another El Niño pattern associated with drought may settle in, or La Niña could return.

We probably need two years, back to back, of classic La Niña to make a real difference, said Roger Stone, professor of climatology and water resources at the University of Southern Queensland in Toowoomba.

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