Chicago wheat futures rose for a third day on Monday, trading near last session's 8-1/2-year top as tightening supplies in key exporting countries buoyed the market.
Soybeans jumped to their highest in more than two weeks, while corn was largely unchanged.
"The rally is about as broad as it can be," said Tobin Gorey, director of agricultural strategy at Commonwealth Bank of Australia, referring to gains in the wheat market.
"The market is still adjusting to lower 2021 crop estimates and the tight supply conditions that implies."
The most-active wheat contract on the Chicago Board of Trade (CBOT) rose 0.4% to $7.65 a bushel by 02:00 GMT, having closed up 1.2% on Friday when prices hit a February 2013 high.
Soybeans were up 0.5% to $13.72 a bushel, after rising earlier in the session to $13.73-3/4 a bushel, the highest sine July 30 and corn was unmoved at $5.73 a bushel.
The US Department of Agriculture last week slashed its forecast of global 2021-22 wheat production and ending stocks, citing poor weather in Russia, Canada and the United States.
Adverse weather has also cut crop prospects in the European Union, contributing to a potentially "explosive" global supply outlook, analyst firm Strategie Grains said last week.
The USDA last week also cut its estimate of US corn production more than most analysts expected.
However, some analysts said acreage data released last week by the USDA's Farm Service Agency implied that the USDA eventually might raise its official estimate of US corn plantings.
The US soybean crush last month was likely the slowest July crush since 2017 due to scattered processing plant downtime and tightening supplies of beans, analysts said ahead of a National Oilseed Processors Association (NOPA) report due on Monday.
Large speculators raised their net long position in CBOT corn futures in the week to Aug. 10, regulatory data released on Friday showed.
The Commodity Futures Trading Commission's weekly commitments of traders report also showed that noncommercial traders, a category that includes hedge funds, trimmed their net short position in CBOT wheat and raised their net long position in soybeans.