The average price for regular gasoline at U.S. pumps jumped 8.5 cents in the past two weeks to a 13-month high of $3.6918 a gallon, according to Lundberg Survey Inc.

The survey covers the period ended April 18 and is based on information obtained at about 2,500 filling stations by the Camarillo, California-based company.

Prices are the highest since March 22, 2013. The average is 15.55 cents higher than a year ago, Lundberg said. Gasoline has risen 39.74 cents a gallon since bottoming out in February and is up 43 cents this year.

“The most important factor right now in this rise is crude oil, which rose by a very similar amount to the street-price move,” Trilby Lundberg, the president of Lundberg Survey, said in a telephone interview Sunday. “From here, we will probably see very little increase, if any, with the big caveat of course being crude. If crude prices climb even higher, then this may not be the peak.”

The highest price for gasoline in the lower 48 U.S. states among the markets surveyed was in Los Angeles, at $4.26 a gallon, Lundberg said. The lowest price was in Salt Lake City, where customers paid an average $3.29 a gallon. Regular gasoline averaged $3.80 a gallon on Long Island, New York.

An “extremely robust” rise in U.S. gasoline demand may have also helped increase retail prices, according to Lundberg. Demand for the motor-fuel in the last four weeks is up 4.6 percent from the same period a year ago, Energy Information Administration data show.

Gasoline futures for May delivery on the New York Mercantile Exchange rose 12.34 cents, or 4.2 percent, to $3.0547 a gallon in the two weeks ended April 17. Trading was closed April 18 for Good Friday.

Inventories of the motor fuel fell 154,000 barrels in the week ended April 11 to 210.3 million, the lowest since Nov. 15, according to Energy Information Administration data. Supplies were down 9.9 percent in eight weeks of contractions as refiners performed seasonal maintenance and sold off stocks of winter-grade gasoline.

Crude inventories climbed 10 million barrels to 394.1 million in the week to April 11, the highest since June, according to EIA data.

West Texas Intermediate crude for May delivery gained $3.16, or 3.1 percent, to $104.30 a barrel on the Nymex in the two weeks to April 17.