The World Meteorological Organization (WMO) advises that La Niña may worsen the chronic drought afflicting Southern California and the southeastern United States, while northern Brazil and parts of Africa receive flooding rains.

Shifts in atmospheric circulation could even rearrange the pattern of sea ice around Antarctica, pushing it toward the Pacific side of the continent.

"This La Niña is now in its developing phase and getting stronger, and we can expect it to peak this coming December and January," said WMO chief Rupa Kumar Kolli.

The U.S. weather agency NOAA predicts La Niña will bring above-normal temperatures across most of the country through December, while the Pacific Northwest and western Canada receive cool and wet conditions.

Animation: NOAA