More than 65 percent of the contiguous United States was under at least "moderate" drought as of September 25, up from 64.82 percent a week earlier, according to the Drought Monitor, a weekly compilation of data gathered by federal and academic scientists.
The portion of the United States under "exceptional" drought - the most dire classification - rose to 6.12 percent from 5.96 percent a week earlier.
Conditions were most severe in the High Plains, with severe or worse drought levels covering 83.80 percent of the region, up from 82.81 percent the prior week, according data gathered by federal and academic climatologists that was released on Thursday.
More than 24 percent of the region, which includes Nebraska, Kansas and Colorado, was in the worst level of drought, dubbed "exceptional."
In Kansas, a top wheat growing state where farmers are now trying to plant their new winter wheat crop, 88 percent of the state was in extreme drought and 51.04 percent was considered in exceptional drought.
More than 95 percent of Oklahoma was in extreme drought, and more than 50 percent of Texas was locked in severe or worse drought levels, according to the data.
In west Texas, the city of San Angelo, Texas, was implementing "Drought Level 3" measures to conserve water, as city officials say they have only enough supply to last 12 more months.
The Commerce Department said Thursday that the drought contributed to a sluggish rise of only 1.3 percent in gross domestic product gains, the slowest pace since the third quarter of 2011. Farm inventories dropped $5.3 billion in the second quarter after slipping $1 billion in the first three months of the year, the department said.
(Reporting by Carey Gillam in Kansas City; Editing by Leslie Gevirtz)