The U.S. Energy Information Administration Monday reported the national average for on-highway diesel fuel was $2.944 a gallon, down 14.4 cents from the previous week and down 48 cents from a year ago.
The highest prices were found in the New England region, with a $3.266 average, while the lowest prices were in the Midwest at $2.888.
Diesel prices hit a record high of $4.764 just four months ago.
Crude oil prices Monday swung wildly in trading on the New York Mercantile Exchange, ending the day at $62.41 a barrel after dipping as low as $59.10 at one point. Oil prices have fallen about 56 percent since reaching a record $147.27 in mid-July.
There is talk that the OPEC oil cartel may meet to further cut production; the group would like to see prices between $70 and $90 a barrel.