The local inflation rate rose to 4.1 percent year-over-year in May, driven by a spike in energy prices, according to federal data released June 12.

The Bureau of Labor Statistics reported that the consumer price index for Los Angeles and Orange counties rose by 0.4 percent in May to an index reading of 266 compared to April and was 4.1 percent higher than the index for May of last year. The national year-over-year inflation rate for May was 2.8 percent.

In Los Angeles County, energy prices rose 4 percent in May and were 14.5 percent higher than a year ago. Gasoline prices alone were up 23 percent from a year ago as the price of oil was around $70 per barrel through most of May. The price of a barrel of oil has since dropped to about $65.

Adding to the rise in gasoline prices in May was the switch by local refineries to the unique California summer blend gasoline and a statewide 12-cent-per-gallon rise in the gasoline tax last November to raise money to pay for road and highway maintenance.

Meanwhile, the price for natural gas jumped 22 percent in May compared to April, according to the BLS, though the price was down 6 percent from a year ago.

Excluding often volatile food and energy prices, the index rose 0.2 percent in May and was up 3.7 percent from a year ago.

The inflation index is calculated by comparing current prices for various consumer products to a three-year average from 1982-1984, which the agency assigned as the base period with a value of 100.

Before last month, the last time the local year-over-year inflation rate topped 4 percent was in the summer of 2008 when it peaked at 5.7 percent, thanks to a spike in gasoline prices as the price for a barrel of oil briefly hit $145.

Economy, education, energy and transportation reporter Howard Fine can be reached at [email protected]. Follow him on Twitter @howardafine.