MERCED -- The mercury isn't the only thing that's rising in the San Joaquin Valley these days.
For those who've been too busy watching temperatures climb into triple-digit territory and remain there the past week or so, including hitting 104 in Merced on Monday, they might want to check out the price of gas.
It's also been soaring, burning consumers for an additional 39 cents per gallon in the past month, according to data from the mercedgasprices.com website. The average pump price in Merced now stands at $4.07.
The price increase was even more intense over the past week, when a gallon of gas jumped 23 cents following an Aug. 6 blaze at a Richmond refinery that produces a large amount of the gasoline that satisfies California's clean-air rules, which are the toughest in the nation. Other parts of the refinery, which supplies 16 percent of California's daily gas consumption, are still producing fuels. But the refinery's reduced output has sent gas prices rising.
Investigators looking into the cause of the fire Monday were waiting for structural engineers to determine if it was safe for them to enter the unit. Federal, state and company inspectors hoped to get the all-clear and gain access to the fire site after the safety work was completed.
David Slinkard is well aware of the sharp rise in gas prices recently. Filling up his Volvo at an Arco station Monday in Turlock, Slinkard said he drove from Washington "and it cost an arm and a leg to get here."
Slinkard, 55, ran a paint contracting business in Turlock for 20 years before the housing market fell apart in 2008. Now he's back in school -- coincidentally, to earn a license to work as an operator in an oil and gas refinery.
"I'd rather be on that end of things," he said.
Amar Singh, a cashier at the Arco station in Turlock, said customers have asked him about the sharp uptick in prices, which are set by the supplier.
"Last week, it seemed like it was going up, up, up, 6 cents every day," he said, adding that prices seem to have stabilized in the past few days. "I think we're good, but I'm not sure."
Prices are on the rise nationally as well. The average price of a gallon of gas was up 34 cents since July 1, according to AAA.
The current price bump marks the third spike in gas prices in the region in 2012. In February, crude oil prices jumped as speculators traded on fears of an Iranian blockade of shipping lanes, and in May, a fire at a refinery in Washington caused another price jump.
Busy time for refiners
Seasonal factors also are sending pump prices higher. Gas usually costs more in the late spring and summer because refiners have to make more expensive blends of gasoline to meet clean air rules, and because the summer driving season boosts demand.
In the past few weeks, pipelines serving Wisconsin and Illinois ruptured, and refineries were shut down unexpectedly because of equipment problems in Illinois and Indiana.
Gasoline prices shot up more than 50 cents in the span of a month in Illinois, Indiana, Kentucky, Michigan, Ohio, Vermont and Wisconsin.
Modesto Bee staff writer Patty Guerra contributed to this report.