Gas prices reached an all-time high in California this week, leading to Gov. Jerry Brown allowing early use of the cheaper winter blend gasoline formula in the state.

Over the past week, prices have gone up 50 cents to a state average of $4.67 as of Oct. 10.

“A perfect storm of events happened across the state, which has been catastrophic for prices,” Marie Montgomery, the spokesperson for the Automobile Club of Southern California said.

There was a refinery fire in Richmond in August that halted production on the summer blend of gasoline, which is only used in California because of stringent air quality restrictions, Montgomery said.

The main difference in the winter and summer blends is that there is less hydrocarbons in the summer blend, which allows it to burn cleaner during the hotter months, Montgomery said. That also lowers summer blend’s evaporation rate which would make a car harder to start in cold temperatures, according to NPR.

“The gas companies didn’t want to make more of the summer blend because they didn’t want to have a surplus when we made the shift to the winter blend,” Montgomery said.

When a few more refineries ran into problems across the state, the summer blend’s inventory got too low and it caused prices to go up. Winter blend gasoline usually starts being made at the end of October, but Gov. Brown allowed the production of winter blend early because of the summer blend shortage, Montgomery said.

After gas stations sell off all of their summer blend, Montgomery hopes consumers will begin to see the prices come down a bit.

“Gas prices will never come down like they went up,” she said. “We’re not going to see a 50 cent drop in a week, but we hope they’ll start to come down sooner than later.”