MELBOURNE, Australia — El Nino is back.

Australia has declared the event for the first time since 2010 and says it will probably be “substantial.” Japan also said El Nino had emerged.

The tropical Pacific is in the early stages of the pattern that can bring drought to parts of Asia and rains to South America, and ocean temperatures will probably stay above thresholds through the Southern Hemisphere winter and at least into spring, the Australian Bureau of Meteorology said Tuesday.

The last El Nino was from 2009 to 2010, and since then the Pacific has either been in its cooler state called La Nina, or neutral. The pattern can crimp the hurricane season in the Atlantic, bring more rain across the southern United States and warm some northern states.

Warm anomalies in the Pacific in March and April were very similar to those observed in 1997, a year of an “intense” El Nino, Meteo-France said.

“It’s come on quickly and all of our model guidance predicts it’s going to continue to strengthen,” David Jones, manager of climate monitoring and prediction at the bureau, said by phone. “A significant or substantial event is likely.”

The effects have already been felt before the official declaration. Morgan Stanley said in December that weather in South America for much of the previous month had been typical of an El Nino, citing above-normal rain in Argentina and southern Brazil and dry conditions in northeast Brazil. Palm oil, cocoa, coffee and sugar are the crops most at risk, Goldman Sachs reported last year.

The monsoon in India, the world’s second-biggest producer of sugar and wheat, may be below normal for a second year as the event develops, said Harsh Vardhan, the country’s minister of science and technology and earth sciences. El Nino is causing dryness in the Philippines, Oil World, a Hamburg- based researcher, said this month.

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