BUENOS AIRES, Nov 15 (Reuters) - Argentina's agricultural core saw much higher than average rainfall during the first half of November and will likely see even more moisture in the coming days in a welcome boost for the sector, the Rosario grains exchange (BCR) said on Wednesday.

The rains coincide with the weather phenomena known as El Niño, which for Argentina means higher levels of precipitation over key farmland following a dry Southern Hemisphere winter.

Argentina is a major global grains exporter, especially for processed soybeans, corn and wheat.

"We're beating the accumulated historical levels for November by a big margin," said Cristian Russo, the BCR's chief forecaster, in the report.

The stock exchange noted that since Tuesday the core area's northwestern farmland got 15-40 millimeters (0.6-1.6 inches) of rain, with "significant and more generalized" precipitation expected, which should boost farm production.

Not only is Argentina's grains output a key pillar of economic activity in the South American country, but it also represents a much-needed source of U.S. dollars for the cash-strapped central bank needed to finance exports and pay down debt.

In a separate weekly report issued Wednesday from the Buenos Aires Grains Exchange (BdeC), over the next week Buenos Aires province will likely see 10-50 millimeters (0.4-2.0 inches) of rain.

Other parts of Argentina's fertile Pampas region are seen receiving more moderate moisture of up to 10 millimeters (0.4 inches), according to BdeC.

Recent rainfall over the last few weeks have provided a welcome boost to the start of soybean planting for the 2023/2024 harvesting season, while also helping areas planted with corn for the same cycle, though most corn plantings have yet to be sown.

BCR estimates that the 2023/2024 soybean crop will likely yield 50 million metric tones and the corn crop another 56 million tons. (Reporting by Maximilian Heath; Editing by David Alire Garcia and Cynthia Osterman)