Need to fill up? Don't wait until morning! Otherwise, you'll basically be paying 12 cents per gallon more.
Here's a more detailed look from the LA Times:
The bill signed by Gov. Jerry Brown will raise the state excise tax on gasoline by 12 cents, from 29.7 cents per gallon to 41.7 cents per gallon. The excise tax on diesel fuel will increase by 20 cents, from 16 cents per gallon to 36 cents per gallon, and the sales tax rate on diesel will increase from 9% to 13%.