NEW YORK—Wheat prices jumped above $9 a bushel Wednesday on expectations that warm, dry weather in Argentina and Australia will hurt crops and tighten world supplies.

In other commodities trading, crude ended higher for a second day while gold and silver prices also rose.

Wheat for December delivery surged 29.25 cents to settle at $8.995 a bushel on the Chicago Board of Trade, after earlier rising to $9.03 a bushel.

Wheat’s rally boosted other agriculture futures. December corn added 10.5 cents to settle at $5.95 a bushel, while November soybeans rose 24 cen...