The DOE's Energy Information Administration reports the national average for diesel is $3.965, which is 13 cents higher than it was a year ago. On the other hand, it's lower than the $4.147 peak hit on March 26.
California diesel prices jumped more than 19 cents per gallon to $4.215, the highest in the nation. The lowest average diesel prices were in the Gulf Coast region at $3.856.
Average gasoline prices rose to $3.721, which is 11.7 cents higher than a year ago.
Contributing to high diesel and gasoline prices on the West Coast is a fire that knocked out a key section of one of the nation's largest oil refineries.
Meanwhile, U.S. crude oil futures fell Monday. The U.S. benchmark, West Texas Intermediate or WTI, settled down 14 cents, or 0.2%, at $92.73 per barrel, following choppy trading. Unusually, Brent crude oil, the benchmark for the European continent, rose to $113.60 per barrel.