NEW YORK—Soybeans rose to a record for a third day Thursday but later eased back on expectations that warm, dry weather in the Midwest will help crops bounce back after flooding last month.

Other commodities traded mixed, with crude oil briefly rising above $145 for the first time and gold, silver and copper futures falling.

Soybean futures have shot up 9 percent in the last week, driven by concerns of poorer-than-expected U.S. yields following devastating Midwest floods that ravaged corn and soybean fields. But weather forecasts for the next few days predict favorable ...