Brazilian producers will harvest 120.39 million tonnes of soybeans in the season that began in September, a rise of 0.9 percent compared with the previous cycle, according to the average of 12 estimates collected by Reuters.

Area planted will also reach a record 36.12 million hectares (89.3 million acres), according to the average of nine analyst forecasts.

Rains at the start of the crop year have helped planting to advance at the fastest pace in years, said Victor Ikeda, an analyst at Rabobank.

"There's still a lot of road ahead to the harvest, mainly in terms of how the weather develops," he said. But assuming the current trend, Rabobank expects Brazilian production to reach 123 million tonnes, Ikeda said.

Aedson Pereira, an analyst at consultancy IEG FNP, said that Brazil may surpass the 120 million tonnes mark this season, as "for now, there are no factors likely to push yields lower."

To be sure, last week there were some signs in the state of Paraná, Brazil's second-largest soy producer, of excess moisture, farmers said, but this has yet to affect productivity.

According to Refinitiv's Agriculture Weather Dashboard, abundant rains will continue through the beginning of November in Paraná and likewise in Mato Grosso do Sul state.

No. 1 soy-producing state Mato Grosso, on the other hand, may have below-average rains, the data showed.

The planted area is expected to expand for Brazil's "first corn" crop, which is planted in the southern hemisphere's summer.

Poll data projects first corn output of 27.48 million tonnes, up 2.5 percent from the previous year. First corn planted area is expected to expand 5.5 percent, to 5.36 million hectares, from the prior season.