The Wapsipinicon River trickles over the dam at Independence on Friday, Oct. 5, 2012. The river was flowing at a rate of 4.8 cubic feet per second on Friday morning, barely one hundredth of its normal flow in early October. The river was at its fourth-lowest flow for that date in the 80 years that records have been kept at that guage. At least four other Eastern Iowa streams, including the Iowa River below the Coralville dam and the Wapsipinicon at Tripoli, had attained record low flows. (Orlan Love/The Gazette)

A new report shows that the nation’s worst drought in decades has worsened for a second straight week, after conditions had improved for more than a month.

The weekly U.S. Drought Monitor report released Thursday shows that 62.7 percent of the continental U.S. was in some form of drought as of Tuesday. That’s up from 60.1 percent the previous week.

The portion of the lower 48 states in extreme or exceptional drought — the two worst classifications — also rose, to 20.12 percent from last week’s 19.04 percent.

The dry conditions intensified sharply in Oklahoma, where 90.5 percent of the state is in extreme or exceptional drought. That’s up 19 percentage points.

The portion of South Dakota in those two classifications rose more than 8 percentage points, to 63.32 percent.