ST. LOUIS — Extreme drought conditions have spread in several Plains states, but recent rainfall has slightly reduced the overall area of the lower 48 states experiencing some form of drought, according to the latest U.S. drought map.

Nearly two-thirds of the lower 48 states is experiencing some drought, although recent storms pushed the percentage down to 62.91, from last week's 63.86, according to the U.S. Drought Monitor map posted Thursday on its website.

The survey, based on conditions as of Tuesday morning, found that the area experiencing extreme drought — the second highest classification behind exceptional drought — rose nearly 2 percentage points from the previous week, to 22.3 percent. This was due largely to a worsening of conditions in parts of Kansas, Missouri, Nebraska and Oklahoma.

The area facing exceptional drought also increased, from 2.38 percent to about 3 percent.

Some areas benefited slightly from rains that "will settle the dust" but still won't be sufficient to salvage parched crops, National Drought Mitigation Center climatologist Brian Fuchs said by phone from the University of Nebraska in Lincoln, where the weekly drought report is released.

"There are rain events that did take place, but we didn't see any widespread improvement to the core drought areas," Fuchs said. Such precipitation "probably held off the intensification for a week or so. But the heat is going kick back in, and we're going be in the same situation.

"The heat kicks in and the dryness returns. To say that we've seen good widespread rain throughout the drought regions of the county, we just haven't. It's beneficial in some aspects, but in agricultural aspects it's too late."

On Wednesday, the U.S. Agriculture Department added 218 counties from 12 drought-stricken states to its list of natural disaster areas, bringing the overall total to 1,584 counties in 32 states. That's more than half of all U.S. counties, and the vast majority of them received the designation because of drought that's considered the worst in decades in many prime farming areas.

The USDA uses the weekly Drought Monitor to help decide which counties to deem disaster areas, with the distinction making farmers and ranchers eligible for federal aid that includes low-interest emergency loans.

As of this week, nearly half of the nation's corn crop was rated poor to very poor, according to the USDA's National Agricultural Statistics Service. About 37 percent of the U.S. soybeans were lumped into that category, while nearly three-quarters of U.S. cattle acreage is in drought-affected areas, the survey showed.

The potential financial fallout in the nation's midsection appears to be intensifying. The latest weekly Mid-America Business Conditions Index, released Wednesday, showed that the ongoing drought and global economic turmoil is hurting business in nine Midwest and Plains states, boosting worries about the prospect of another recession, according to the report.