Pump prices increased 10 cents to $2.83 per gallon for the week with the West Coast taking the brunt of a nearly 20-cent increase as refinery maintenance is causing tighter gasoline supply, according to AAA.
For the week ending April 15, California's average pump price reached $4, which is the most expensive state average since July 2014.
The national average price is now 3 cents higher than a month ago and 12 cents higher than a year ago.
"We are seeing very expensive gas prices for this time of year across the country," said Jeanette Casselano, AAA spokesperson. "Motorists are seeing prices increase as gasoline stocks decreased substantially by 7.7 million barrels amid summer-like demand readings."
National gasoline prices have been moving higher since Feb. 4, when they sat at $2.26 per gallon. At the time, the price was near a two-year low.
States with the largest weekly increase include California (20 cents), Nevada (18 cents), Missouri (13 cents), Oregon (12 cents), Alaska (12 cents), Washington (12 cents), Utah (12 cents), Colorado (12 cents), Idaho (11 cents), and Kansas (11 cents).
States with the least expensive markets include Alabama ($2.50), Mississippi ($2.51), Arkansas ($2.52), South Carolina ($2.52), Louisiana ($2.54), Texas ($2.57), Virginia ($2.57), Oklahoma ($2.59), New Hampshire ($2.59), and Missouri ($2.60).
Meanwhile, the average price of diesel fuel increased 2.5 cents to $3.118, which is 1.4 cents higher than a year ago, according to the U.S. Energy Information Administration.