Experts predict a run of severe weather in the coming months, with devastating floods striking some parts of the world while severe droughts afflict other regions, as the climate phenomenon known as La Niña gathers momentum.

A chronic drought afflicting southern California and many southeastern states of America could be exacerbated, with Los Angeles heading for its driest year on record. In contrast, western Canada and the northwestern US could turn colder and snowier. Mozambique, southeast Africa, and northern Brazil may face exceptionally heavy rains and floods, while southern Brazil and much of Argentina suffer drought.

La Niña could even rearrange the pattern of sea ice around the Antarctic, pushing the ice pack towards the Pacific side of the continent. Already, torrential rains have triggered severe floods across a huge swath of Central Africa, stretching from Senegal in the west to Uganda in the east.

Rupa Kumar Kolli, chief of world applications at the World Meteorological Organisation (WMO) in Geneva, predicts that the worst of La Niña is yet to come. "This La Niña is now in its developing phase and getting stronger, and we can expect it to peak this coming December and January," he said. Whether this episode of La Niña will make itself felt in Britain and continental Europe this winter is not certain. "We tend to get a mild end to winter with La Niña, but it's not a strong signal," said Adam Scaife, at the Hadley Centre of the Met Office in Exeter.