The national average retail price of regular gasoline fell 5.8 cents to $3.367 a gallon in the week ended Monday, the Energy Information Administration said.
Prices were at their lowest level since Jan. 28 for a second straight week.
Prices have fallen 24.1 cents, or 6.7%, over the past five weeks as the peak summer demand season has passed and inventories remain high.
Gasoline prices are down 12.5%, or 48.3 cents, from a year earlier, the biggest year-on-year decline since Oct. 12, 2009, EIA data show.
Current gasoline prices are 18.2 cents below the record national average of $4.114 a gallon hit July 7, 2008, the EIA data show.
In its September short-term energy outlook, the EIA projected gasoline prices will average $3.55 a gallon this month, down from $3.75 a gallon a year earlier.
The forecast is based on Nymex crude-oil futures averaging $103 a barrel, up from $89.49 a year earlier. Nymex crude is averaging $103.26 a barrel so far this month.
Internationally traded Brent crude oil, which holds sway over gasoline prices, is expected to average $110 a barrel this month, down from $111.21 a barrel last year. Brent is averaging $109.05 a barrel so far this month.
The EIA said crude-oil costs accounted for 71% of the price of gasoline in August.
Prices dropped in all regions, led by a 7.3-cent decline in the Midwest.
AAA said Monday its daily average price was $3.346 a gallon, down 5.3 cents from a week earlier. The price was 23.2 cents lower than a month earlier, and 46.8 cents below the year-earlier level.
Region Change Vs Price
Week Ago Per Gallon
East Coast -4.6c $3.363
Midwest -7.3c $3.275
Gulf Coast -4.9c $3.127
Rocky Mountains -4.2c $3.507
West Coast -6.5c $3.737
California -8.2c $3.850
