Chicago wheat edged lower on Thursday, extending two-day losses to nearly 3 percent, after rain relief forecast for U.S. crops halted a recent short-covering bounce.

Corn and soybeans were almost unchanged after touching one-week lows earlier in the session. Investors were bracing for U.S. government planting and stocks reports later in the day that are among the most watched publications of the year in grain markets.

The most active wheat contract on the Chicago Board of Trade fell 0.3 percent to $4.62-1/2 a bushel by 1044 GMT, after closing down 2.7 percent in the previous session. The two-day fall wiped out similar gains on Monday and Tuesday when concerns about dry, chilly weather prompted some short-covering.

Although a portion of the hard red winter wheat belt could remain dry, updated forecasts indicate better chances of rainfall in the central and southeast plains in the next two weeks, the Commodity Weather Group said.

"The rainfall, if (it) actually happens, is good news for crops in the dry western reaches of the [hard red wheat] region," said Tobin Gorey, director of agricultural strategy, Commonwealth Bank of Australia.

The expected rain relief has put the focus back on bearish supply fundamentals marked by rising wheat stocks in the United States and worldwide.

But price movements were limited as grain markets awaited the U.S. Department of Agriculture's spring planting and quarterly stocks reports at 1600 GMT.

Analysts polled by Reuters expect the USDA to project higher corn and soybean areas, despite lower prices this year, and also peg March 1 stocks at their highest in years.

The most active soybeans futures contract were unchanged on the day at $9.09 bushel after earlier hitting a one-week low of $9.05-1/4 a bushel. The most active corn futures inched down 0.1 percent to $3.66-1/2 a bushel, just off a one-week low of $3.66-1/4 earlier in the session.

Grain markets were also awaiting weekly U.S. export sales figures at 1230 GMT for a fresh indication on demand.