[Wonder Warthog]

"Here in CA, too. One station all grades are over $4 already! Of course, that includes Moonbeam’s recent huge gas tax increase."

In California and a few other states, refineries are forced to produce "boutique gasolines" specially blended to "reduce emissions". Those specialized fuels are produced in smaller quantities and are thus more expensive.

[ProtectOurFreedom]

I found an interesting page about summer blend gasoline. By mid April, refineries have switched over to summer blend and the peak annual price typically occurs in the April - May timeframe. See Why Prices Historically Go Up in Spring.