Wright Express (WEX) has released the latest edition of its fuel prices index, noting that retail gasoline prices surged in August to an average of $3.83, which is the highest level since the end of April.

The price of gasoline increased 30 cents between the beginning and end of August. WEX cited the same reasons for the rise in prices as others have recently, including several refinery issues and Hurricane Isaac, along with the use of summer spec gasoline during the driving season.

For fleet managers concerned about how far prices will really drop, WEX said the drop could be substantial. The switch to the less-expensive type of is set for Sept. 15, WEX stated. The company said some analysts are forecasting a major drop in prices — up to 50 cents per gallon, by Thanksgiving (barring unforeseen supply disruptions).

Diesel prices are back above $4 per gallon, on the other hand, and WEX stated that industry analysts expect prices to go even higher in the near future due to supply constraints.

Wright Express Monthly 
Price Per Gallon Average Report for 
August 2012

Atlanta GA $3.67 $3.94
Boston MA $3.75 $3.98
Chicago IL $4.18 $4.02
Dallas TX $3.55 $3.82
Denver CO $3.47 $3.90
Detroit MI $4.01 $4.04
Houston TX $3.52 $3.79
Los Angeles CA $4.10 $4.29
Memphis TN $3.52 $3.84
Miami FL $3.78 $4.00
Minneapolis MN $3.71 $3.96
New Orleans LA $3.55 $3.79
Philadelphia PA $3.75 $4.05
Phoenix AZ $3.43 $3.92
Portland OR $3.90 $4.09
San Francisco CA $4.16 $4.38
Seattle WA $3.97 $4.32
St. Louis MO $3.63 $3.83
Washington DC $3.99 $4.17
National Average U.S. $3.70 $3.95

The chart below shows gasoline and diesel price trends.

Source: Wright Express

Source: Wright Express

To see last month's fuel report from Wright Express, click here.