Last month was the hottest July and the hottest month on record for the contiguous United States, 3.3 degrees above the 20th century average, scientists said.

The average of 77.6 degrees topped the previous warmest July, which was in 1936 when the average U.S. temperature was 77.4 degrees, a release from the National Oceanographic and Atmospheric Administration reported Wednesday.

July capped the warmest 12-month period the United States has experienced since weather record keeping began in 1895, NOAA said.

Drought accompanied the record temperatures, expanding to cover around 63 percent of the lower 48 states, the U.S. Drought Monitor reported.

The peak value of 63.9 percent reached on July 24 is a record in the 13-year history of the USDM, climatologists said.

The area of the country suffering the worst drought categories -- extreme to exceptional drought -- doubled from 10 percent in June to 22 percent in July,

Drier-than-average conditions continued across the Central Plains and Midwest during July, as Nebraska, Iowa, Illinois, and Missouri had July precipitation totals ranking among their 10 driest, NOAA said.