By Jesse Newman

CHICAGO--Grain and soybean futures rebounded Monday, buoyed by ongoing concerns over world weather and fund buying.

Soybean prices bounced off a seven-week low, shored up by worries that Argentina has received too much rain, which could imperil the nation's harvest. Although excess dryness was originally the concern in Argentina, subsequent rainfall and flooding in some parts of the country are now casting uncertainty over the size and health of its soybean crop.

Traders each year are closely tuned to the weather in South America, which is a major U.S. rival for soybean production and export. Some analysts expect Brazil's soybean harvest to top one million metric tons this season, which would add to already adequate world supplies of the crop at a time when foreign buyers are shifting purchases from the U.S. to South America.

Soybean futures for January gained 10 1/2 cents, or 1.1%, to $9.96 1/2 a bushel at the Chicago Board of Trade.

Corn and wheat prices advanced amid buying by index funds, which analysts say are rebalancing their investment portfolios this week. Funds have been holding large short positions in the grain markets for months now, and some are likely unwinding bets that prices have further to fall in the short term.

Prices for corn also lifted as traders squared positions ahead of a government crop report due out on Thursday. Analysts widely expect the U.S. Agriculture Department to cut its estimate for the nation's 2016 corn harvest, while also offering a lower forecast for domestic and world stockpiles. Still, the corn market could be little moved by the USDA's release this week, since the world remains oversupplied with grain.

CBOT March corn climbed 2 cents, or 0.6%, to $3.60 a bushel.

Lingering cold temperatures in the U.S. Plains helped shore up the wheat market, as chilly weather can damage crops unprotected by snow cover.

Prices for the grain also benefited from expectations that the USDA will project farmers this season seeded 5% fewer acres of winter wheat than last, which could lead to a smaller harvest.

CBOT March wheat futures rose 4 cents, or 1%, to $4.27 1/4 a bushel.

Write to Jesse Newman at jesse.newman@wsj.com

(END) Dow Jones Newswires

January 09, 2017 16:10 ET (21:10 GMT)

Copyright (c) 2017 Dow Jones & Company, Inc.