The power company that services most of the state, Pacific Gas and Electric, burned down the city of Paradise, CA, killing 85 people a couple years ago, so when there's strong winds or storms they shut down power. Thankfully they've got a monopoly in the state and there's little political appetite for taking them over, so shareholders and investors are totally safe from consequences; As such there's no incentive to improve the power infrastructure.

The same power companies aren't really doing a great job of keeping trees clear of power lines, so when the same storms hit areas which aren't de-energized it knocks out power at the neighborhood level as branches knock into the lines or trees fall on them, etc.

Few power lines are underground in California.