Summer blend fuel: What it is and why it's more expensive

(NEXSTAR) – It may not feel like summer in much of the country, but gas pumps nationwide are starting to deliver their summer blends. Though it has environmental benefits, the switch may hurt your wallet.

Within a week, prices at pumps across Wisconsin jumped by roughly 20 cents, sending the cost of a regular gallon of gasoline from around $3 to as much as $3.27, Nexstar’s WFRV reports. A spokesperson for AAA said the rollout of the summer fuel blend may be partially to blame for the price hikes.

It isn’t just Wisconsin that receives special fuel for the warmest time of the year.

AAA spokesperson Devin Gladden tells Nexstar the summer blend stems from regulations from the U.S. Environmental Protection Agency that were enacted by Congress in 1990.

“The EPA sets regulations in the summer for communities that suffer from high and rather poor air condition based on smog and other particulate matter,” Gladden explains. “In the summer, that can become particularly more toxic and more pollutants can get trapped because it’s hot.”

From June 1 to September 15, the EPA regulates gasoline based on its “Reid vapor pressure,” or RVP. Because gasoline can evaporate easier during these warm summer months, the EPA requires gasoline to have a lower vapor pressure, which reduces air pollution. Winter-grade gasoline has a higher vapor pressure so your engine can start more easily.

Gas must meet a maximum per-gallon RVP, or Reid vapor pressure, of 9.0 psi unless the fuel is being sold in an area required to meet a lower RVP. Areas in Colorado, Nevada, Oregon, Texas, and Utah are required to meet a lower RVP of 7.8 psi. California has its own fuel, California reformulated gasoline, that is specially formulated to burn cleaner.

The switch to the summer blend will cost you more because producing the summer-grade gas is more expensive, Patrick De Haan, lead petroleum analyst at GasBuddy, told Nexstar.

Even during this transition period, prices at the pumps may rise as refineries tend to perform maintenance during spring to ensure they’re ready for summer’s high demand.

As of Thursday, the national average for a gallon of regular gasoline, according to AAA, is $3.47.

Alix Martichoux contributed to this report.