The average price of diesel dropped last week for the first time in a month, according to weekly figures released Monday by the U.S. Department of Energy.

The DOE's Energy Information Administration reported that the national average retail price for on-highway diesel was $3.067, down six-tenths of a cent from last week and down 26.6 cents from a year ago.

The highest prices were seen on the West Coast at $3.243; the lowest prices were reported in the Gulf Coast region at $2.985. Prices in the Gulf Coast and Rocky Mountain regions were the only ones to rise this week.

This is the fourth week in a row the average price of diesel has been $3 or above.