March 12 (UPI) -- Drivers across the U.S. on average paid 5 cents per gallon more to refill tanks on the week ended Monday compared with the previous week because of increased demand.
The national average has been steadily increasing for the last three weeks. "During that time, gasoline stocks have gradually decreased while demand has started to increase," the AAA driver's organization said.
"Pump prices will continue to increase in coming weeks, but AAA does not expect this year's high to be nearly as expensive as last year's peak price of $2.97," said Jeanette Casselano, AAA spokesperson.
Gasoline prices as of Monday were a nickel more than last week, 20 cents more than a month ago, and five cents less than last year, according to the AAA.
Separately, GasBuddy, which also tracks fuel prices, said the national average it found was $2.48 per gallon, up 5 cents on the week. Diesel prices as of Monday were at $3.01 per gallon, or 1.7 cents on the week.
Patrick DeHaan, GasBuddy's head of analysis, said a large part of the rise is because "cleaner burning gasoline is now the predominate fuel being produced."
This is the season in which refiners change to a warmer weather, and more expensive, fuel mix. Seasonal prices in the United States begin to increase in February and continue until the end of May.
In the Mid-Atlantic and Northeast, prices saw some of the highest increases with six mid-Atlantic and Northeast states gaining seven cents per gallon or more. Stocks there have fallen by 6.3 million barrels to 64.9 million barrels, one of the lowest seen in the region this year.
In the South and Southeast, state gas price averages as as much as seven cents more expensive for all but one state. Gasoline stocks fell for a third week.
All states in the Rockies region saw prices rise led by Utah, where the average rose 6 cents per gallon. Gasoline stocks there declined for a third week.
As for the West Coast, gasoline prices are higher in part due to stricter emission standards. At $3.31 per gallon, California and Hawaii are the most expensive markets, the AAA said. The lowest price in the United States is $2.21 per gallon in Missouri.
Changes in the price of blendstock, which normally moves nearly in tandem with crude oil, have caused the increases.
Fuel sold in service stations across most of the United States is a combination of blendstock, like RBOB, or Reformulate Gasoline Blendstock for Oxygenate Blending, later mixed with oxygenate which adds oxygen to the emission to make it cleaner. California mandates a special formula named CARBOB.
These blendstock products are all naphtha obtained from crude oil. The naphtha is in most cases later mixed with about 10 percent ethanol.
RBOB futures for April delivery were quoted Tuesday morning at $1.83 per gallon. This compares with $1.76 per gallon a week earlier; $1.57 per gallon on Feb. 26; and $1.34 per gallon on Feb.5, both for March delivery, according to CME Group data.
Ethanol, alcohol that, in the United States, is mostly derived from corn and added to the gasoline mix as an oxygenate, was quoted Tuesday at $1.30 for April delivery, down from $1.34 per gallon for March delivery a week ago.