LOS ANGELES (CBSLA) — Early in the pandemic, drivers saw lower gas prices, but now the cost of gas appears to be on the rise.

Experts say the price of oil is a major factor in current prices and there’s also California’s springtime switch to the more expensive summer-blend gasoline.

According to the U.S. Energy Information Administration, refiners are required to switch to summer-grade gasoline by a certain date to be in federal compliance.

“Summer-grade gasoline has a lower volatility than winter-grade gasoline to limit evaporative emissions that normally increase with warm weather and cause unhealthy ground-level ozone,” according to the EIA’s website.

A gallon of self-serve regular gas averaged $3.99 across L.A. County, which is up 2.7 cents a gallon from a week ago, 9.5 cents from a month ago, and up $1.08 compared to this time last year.