(Bloomberg) -- California warned that it may not have enough power to keep air conditioners humming Friday as a dangerous heat wave grips the Golden State.

The state grid operator said there could be a shortfall in power supplies Friday afternoon and called for additional resources to help meet electricity demand, according to an alert issued Thursday. The California Independent System Operator, which controls electricity flows on most of the state’s grid, already has asked residents to cut back on power as the heat intensifies heading into the weekend.

Electricity prices have already hit two-year highs as weather forecasters called for excessive heat. Temperatures are forecast to hit 112 degrees Fahrenheit (45 Celsius) Friday in the San Joaquin Valley. Los Angeles could hit 96. Sacramento is forecast to be 108, according to the National Weather Service.

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