LITTLE ROCK — Three times as much of Arkansas was designated under exceptional drought condition Thursday — the worst category — as a week ago, the National Weather Service said.

Just under 11 percent of Arkansas, largely in the east-central part of the state, was categorized under exception drought compared to 3.25 percent last week, the weather service said.

All of Arkansas is abnormally dry, with 96 percent of the state under severe drought conditions Thursday, NWS officials said, though parts of southern Arkansas showed some improvement from drought conditions after receiving a more generous portion of rain that fell over much of the state in the past week.

Overall, amounts of rain exceeding 1 inch were limited.

The state Forestry Commission listed all 75 counties as under high danger of forest fires Thursday, and burn bans were in effect in 51 counties.

The weather service said evaporation easily exceeds a one-third of an inch a day on hot days this time of year, and evaporation can approach one-half inch per day when humidities are low, so rainfall of one-half or three-fourths of an inch has an effect only for a short time.

The weather service forecast slight chances of showers and thundershowers through the weekend with afternoon high temperatures reaching triple digits in some places.