RIVERSIDE, Calif. -

The average price of a gallon of self-serve regular gasoline in the Inland Empire rose 1 cent today to $4.279, its highest amount since March 2, 2013.

   The average price in Riverside and San Bernardino counties is 1.4 cents more than a week ago, 27.3 cents higher than a month ago and 37.3 cents above what it was one year ago, according to figures from the AAA and Oil Price Information Service.

   The rising prices stem in part from the increased cost of ethanol and extended refinery maintenance, reducing the supply, according to Jeffrey Spring of the Automobile Club of Southern California.