Argentina lost an estimated 9 million tonnes of soy in the April storms that swamped the Pampas farm belt, an analyst with the state weather agency said on Monday, forecasting a 15 to 16 percent drop in production from the world's No. 3 exporter.

The sun has come out but too late to help the hardest hit areas. Big importers like China are already looking to the U.S. Midwest to make up for a likely drop in Argentine supply.

The first three weeks of April saw record downpours in Argentine soy provinces Entre Rios, Santa Fe, Buenos Aires and Cordoba, bringing harvesting to a halt. A cold front has since pushed the rain off the Pampas, allowing soils to dry out enough to support the 30-tonne combines used to bring in the crop.

"We estimate total production losses at 9 million tonnes so far. That's a preliminary estimate," said Stella Carballo, chief analyst with the government's Climate and Water Institute.

"The floods are receding and harvesting has resumed, but the effects are lingering," she said. "We had 19 straight days of rain combined with warm weather right at the end of the growing cycle; ideal conditions for crop diseases that reduce yields."

The Buenos Aires Grains Exchange last month chopped its harvest forecast to 56 million tonnes from 60 million. The farm ministry forecasts a 57.6 million tonne crop, warning that estimates will likely fall once the extent of damage becomes clear. Growers are meanwhile selling damaged beans at a discount.

In Santa Fe alone, soy yields were pounded 18 percent lower by the early April rains, said Sofia Corina, an agronomist with the Rosario grains exchange. The province had originally been expected to produce 4 tonnes per hectare.

Last month the exchange estimated a nationwide crop of 59 million tonnes. The projection "is certain to be lowered" when it issues its next crop report on May 11, Corina said.

After soybeans are harvested, Argentine farmers will concentrate on bringing in their 2015/16 corn, which has been less affected by the rains.