The West Coast, typically the site of the nation's highest fuel prices, experienced a slight decline in diesel prices this week as well. Prices there fell an average 2.4 cents per gallon to land at $4.40.
Gasoline prices also saw an increase this week. The national average price for a gallon of gasoline rose 3 cents to $3.88.
Wall Street overall saw a rapid drop in oil prices on Monday. In merely a few minutes' time, Brent crude oil futures prices dropped $5 from $115.20 per barrel to $111.60.
Many attribute the fast selloff to high-frequency computer trading program.
U.S. crude oil futures for October also fell on Monday, by $2.38 per barrel to $96.62.