Conditions for the cotton crop in the U.S., the world’s biggest exporter, are deteriorating as dry weather erodes planting prospects in Texas, the top state grower.

In the week ended Aug. 25, 43% of the domestic crop was in good or excellent condition, down from 49% a week earlier, the U.S. Department of Agriculture said Monday in a report. In Texas, 34% got the top ratings, down from 42% a week earlier and 52% two weeks ago.

About 25% of crops in West Texas, the biggest producing region, will get rain in the next two days, though high temperatures and the resumption of dry conditions will keep soil moisture in a deficit, Drew Lerner, the president of World Weather Inc. in Overland Park, Kansas, said in a telephone interview.

Texas may produce 8.43 million bales, or 37% of U.S. output this season, up from 6.88 million last season, the USDA said on Aug. 12. A bale weighs 480 pounds, or about 217 kilograms .

“Yields could come down due to dryness” in parts of Texas, Sid Love, the president of Sid Love Consulting Services in Overland Park, Kansas, said in an email. “If that is the case, world numbers could be high” as estimated by the USDA, and that may lend support to prices, he said.

On ICE Futures U.S. in New York, cotton has tumbled 20% this year, partly on signs that the U.S. will reap a big harvest, helping to shift the world balance into a surplus in the season that started this month.