SAO PAULO, Aug 25 (Reuters) - The return of the El Nino weather phenomenon should boost South American soybean production as more rainfall can help farmers recover from this season's severe drought in the lower latitudes of the continent, according to meteorologists and grain analysts.

El Nino, a pattern that raises the temperature of surface waters in the Pacific Ocean, is expected to be of mild to moderate intensity, experts forecast, boosting farmers prospects in Brazil's southernmost state of Rio Grande do Sul and in neighboring Argentina.

While Brazil could set a new soybean production record of around 160 million metric tons in the 2023/24 cycle, Argentina's soy output could almost double, analysts say.

"It is a very classic El Nino, with above-average rainfall in Southern Brazil and below average in the North and Northeast," said Safras & Mercado analyst Luiz Roque.

As rainfall returns to Argentina, Roque forecasts soy output at 45-48 million tons there, compared with 25 million tons in 2023, according U.S. Department of Agriculture data.

If favorable weather conditions are confirmed throughout the season, Brazil, Argentina and Paraguay would dominate global export markets too. According to the USDA, they may export nearly a third of global supplies in 2023/24, estimated at 169 million tons.

Safras & Mercado's Roque says Brazil can produce 163 million tons of soybeans in the season that begins in September. But that projection could be revised lower based on indications that starting in November, the northern half of Brazil, including areas of the Centerwest and Southeast, may receive below-average rainfall.

"We are no longer working with the same yields as in the past crop for the Centerwest and Southeast," he said. "It doesn't mean crop failure, but the maps turn on an alert."

The expectation of another bountiful year would keep soybean prices under pressure and could deter soybean area growth.

Antonio Galvan, president of soy farmer group Aprosoja Brasil, said growers will likely not expand plantings as in previous years, citing low prices. The likelihood of less rain in northern parts of Brazil could reduce overall output, he added.

Meteorologist Desiree Brandt said the more irregular climate tends to affect the Northeast, including states in Brazil's new agricultural frontier known as Matopiba.

While the climate there will not be ideal for crops this season, it will not be as dry as in 2015/16, when a drought brought sizeable crop losses, Brandt said.

El Nino is likely to precipitate spring rains in the Centerwest, when soy planting starts, potentially delaying the start of the sowing work, meteorologist Marco Antonio dos Santos said.

"It will rain very little in the month of September," Santos noted. (Reporting by Roberto Samora in Sao Paulo Writing by Ana Mano Editing by Marguerita Choy)