Rain over the weekend and this week will drag out late season plantings of corn and soybeans in the United States that are already at a historically slow pace, an agricultural meteorologist said on Tuesday.

John Dee, meteorologist for Global Weather Monitoring said from 1.0 to 3.0 inches or more of rain fell over the weekend in the central Midwest and 0.5 inch to 1.5 inches is expected at midweek in the northern Midwest.

"The only planting that will take place will be in the southern two-thirds of Illinois, Indiana and Ohio the next couple of days," he said. "If it were all planted this would be perfect, there was pretty good planting progress last week but not like the week before."

Farmers have been scrambling to plant corn and soybeans through mid and late May in an attempt to catch up from weather delays in April and early May.

In its weekly crop progress report released on May 20, the U.S. Department of Agriculture said corn planting was 71 percent complete, up from 28 percent a week ago but still behind the 79 percent five-year average seeding pace.

USDA has projected U.S. 2013 corn plantings at 97.3 million acres, the largest land area devoted to its production since the 1930s.

Soybean planting progress rose to 24 percent from 6 percent a week earlier, USDA said.

USDA will release updated planting data in its weekly crop progress report late on Tuesday.