Argentina's farmers are starting to worry they're getting too much of a good thing after an unrelenting series of storms that soaked the farm belt in recent months delays planting.

With corn and soybean planting in full swing, boggy fields and roads that have melted into a muddy mess have analysts wondering if expectations for a record harvest might be premature. But farmers still have plenty of time to get the seeds in the ground if several weeks of sunny, hot weather materialize later this month.

Argentina is the world's top soymeal and soyoil exporter, and ranks No.3 in soybean shipments. In corn exports, Argentina shares second place with neighboring Brazil.

Grain and soy exports are Argentina's single biggest hard-currency earners, and an important source of tax revenue for President Cristina Kirchner's government.

A brutal drought in the U.S. this year has underpinned high global grain prices, and international markets are counting on record harvests in Argentina and Brazil to rebuild depleted food stocks.

High prices and wet weather due to the El Nino weather pattern have spurred South American farmers to plant as much grain as they can.

Martin Fraguio, director of Maizar, the corn growers' association, said that higher yields will offset what is expected to be a small drop in planted area due to heavy rain.

"For sure this is going to be the largest crop ever," Mr. Fraguio said of the 2012-13 corn harvest.

Maizar is expecting corn production to reach 25 million to 28 million metric tons, up from the 21 million tons harvested during the drought-ravaged 2011-12 season.

The previous record of 24 million tons was set in the 2010-11 season, according to the Agriculture Ministry.

"As they say, rain makes grain," Mr. Fraguio said.

Even so, farmers will have to pick up the pace of planting to get all of their corn in the ground before the new year. Corn planted later in the season risks damage from early frosts in the Southern Hemisphere's autumn months.

Farmers have only planted about 35% of the corn crop, when under normal conditions they should be about half done, Mr. Fraguio said.

Buenos Aires Cereals Exchange crop analyst Esteban Copati also says that fears of widespread crop losses are overblown.

Much of the flooding is in prime farm land, where drainage is good. Most of the fields will be in top shape if the rain lets up for just two weeks, he said.

"There aren't major problems, just some complications because of the delay," Mr. Copati said.

The Exchange is predicting mostly blue skies over the next week. In addition, the drier, western fringes of the farm belt are enjoying excellent planting conditions, thanks to rain, Mr. Copati said.

Adrian Seltzer, an analyst at brokerage Granar S.A., also downplayed the threat to next year's harvest. It's unlikely that more that 5% of the corn or soy area will be lost due to excessive moisture, he said.