U.S. wheat futures are expected to start near a three-month high Thursday as worries about poor global weather intensify.

Traders predict soft red winter wheat for July delivery, the most actively traded contract, will open 10 to 20 cents a bushel higher at the Chicago Board of Trade. In overnight electronic trading, the contract jumped 14 1/2 cents, or 1.8%, to $8.31 1/2 a bushel.

Supporting prices are increasing concerns a drought in France and excessive rains in the northern U.S. Plains will reduce global output. Rabobank, a closely watched agricultural lender, forecast a world crop of 657.6 million tons, nearly 2% below the U.S. Department of Agriculture estimate, and warned weather problems could present a serious threat. The projection came after influential analyst Strategie Grains on Wednesday ditched earlier expectations of a rise in French wheat production this year, saying the drought has cut the production potential of Western Europe's largest producer.

"We are also now factoring in below trend yields in northern Europe, with production in both Germany and France likely to fall short," Rabobank said, adding there are "a number of crops currently at risk of serious downgrades."

Grain users are on edge over the threats to production after poor weather, including a historic drought in Russia, slashed global wheat output last year. Wheat futures have surged this week on concerns about the problems in Europe and the U.S. but remain 7% below a 2 1/2-year high reached in February.

European wheat futures also have responded to the weather threats, with prices climbing than 3.7% in early trading Thursday. The outlook for weather in Western Europe is unfavorable, with mostly dry conditions expected through next Wednesday, according to Telvent DTN, a private forecaster.

In states in the northern U.S. Plains, such as North Dakota, rainfall is expected to increase through the weekend, slowing the planting of spring wheat. As of Sunday, the crop was 36% sown, 40 percentage points behind the five-year average for that time of year.

The Canadian Prairies are suffering from the same wet weather. Rainfall moving northward out of the northern Plains during the weekend will delay fieldwork and planting, according to Telvent DTN.

"Some crops in the east may not end up getting planted if there is not a major improvement in the weather," the firm warned.

Wheat supplies are under increased pressure because demand has increased after prices dropped to a two-month low last week as part of a broad selloff in commodities. The U.S. Department of Agriculture said export sales for the week ended May 12 reached 789,900 tons, near the high end of traders' expectations and up 43% from the previous week. Top buyers included Iraq, which booked 150,000 tons, and Nigeria, which snapped up 140,100 tons.