DES MOINES, Iowa (AP) — Cooler weather and rain in the middle of the country have slowed the deterioration of the nation's corn and soybean crops, but experts said the drought isn't over and the recent respite won't make much of a difference.

The weekly crop condition report released Monday by the U.S. Department of Agriculture rated the corn and soybean almost the same as the week before and marked the first time months that the news wasn't significantly worse.

In the 18 states that grow most of the nation's corn, the USDA rated 51 percent of the crop as poor or very poor last week. A week earlier, it was 50 percent.

Twenty-six percent of the corn was rated fair, compared with 27 percent a week earlier. Twenty-three percent remained rated good or excellent.

Greg Thessen, director of the Iowa field office for the USDA's National Agriculture Statistics Service, said the rain and cooler temperatures had helped in some cases. In others, the corn hadn't gotten worse because it was already in bad shape.

"Some of those fields that were going to be good will be good now until harvest," Thessen said. "For others, there's not a lot further down it could go."

Some farmers are expected to harvest earlier than usual this year because a warm spring allowed them to plant earlier. Some in Iowa, Illinois and Indiana could begin harvesting in two weeks.

The USDA predicted the nation's biggest harvest ever in the spring, when farmers planted 96.4 million acres of corn — the most since 1937. But it cut its estimate a month ago and again Friday, saying it now expects the nation to produce 10.8 billion bushels, the least since 2006.

The USDA's latest estimate predicts corn farmers nationally will average 123.4 bushels per acre, down 24 bushels from last year, and the lowest average yield in 17 years.

In Iowa, the nation's leading corn producer, the USDA estimated Monday that yield will drop to 141 bushels per acre from 172 bushels last year. Iowa farmers are expected to bring in 1.92 billion bushels, 19 percent less than last year.

The nation's soybean crop also remained mostly stable last week, with 38 percent rated poor or very poor, compared with 39 percent the week before. Thirty-two percent remained in fair condition. Thirty percent was good or excellent, in a slight improvement from 29 percent the prior week.

Cooler, wetter weather could help soybean plants grow larger beans in the pods, but it's too late in the season for plants to produce more pods, Thessen said.

"If we keep close to normal temperatures and get some rain, it probably would have a little impact on soybeans," he said, "but how much is yet to be determined."

And, he cautioned, "the drought's certainly not over."