There is a more than 95% chance that El Niño conditions will prevail from December 2023 to February 2024, a U.S. government weather forecaster said on Thursday, exacerbating the risks of heatwaves and floods across several countries.

The weather phenomenon, a warming of ocean surface temperatures in the eastern and central Pacific, is already spurring natural calamities across the globe, with the stakes seen higher for emerging markets more exposed to swings in food and energy prices.

The Climate Prediction Center's (CPC) latest outlook was a slight upgrade from July, when it forecast a 90% chance of the phenomenon persisting through winter.

Earlier in the day, Japan's weather bureau forecast the chances of an El Nino through the northern hemisphere winter at 90%.

The World Meterological Organization had in May warned that the weather pattern could contribute to rising global temperatures.

"In July, El Niño continued as indicated by above-average sea surface temperatures across the equatorial Pacific Ocean," the CPC said.

Given recent developments, forecasters are more confident in a "strong" El Nino event, with roughly two in three odds of temperatures rising by about 1.5 degrees Celsius (2.7 degrees Fahrenheit) or more in November-January, it added.

The El Nino also threatened global rice supplies, amid a ban on shipments of a crucial variety of the staple from top exporter India, as well as other crops such as coffee, sugar and chocolate from southeast Asia and Africa.

It was also expected to bring drier weather across West Africa, South-East Asia and northern South America, and wetter conditions to southern South America in the second half of the year.

(Reporting by Brijesh Patel and Anjana Anil in Bengaluru; Additional reporting by Seher Dareen; Editing by Bernadette Baum and Mark Potter)