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% of the continental U.S. was in some form of drought as of Tuesday. That's up from 60.1% the previous week.

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

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

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