Millions of Californians have been warned their lights and air conditioning units could go out this week as the state plans rolling blackouts to deal with a record heatwave that has pushed the power grid to the limit.

With the first large-scale outages expected late on Monday, the situation brought an admission from Governor Gavin Newsom that poor planning had left America's most populous state ill-prepared for extremes in demand during the switch to renewable energy.

California has vastly expanded the capacity of solar power, and to a lesser extent wind power, in the past decade. The state also allowed a large nuclear power plant to shut down and has curtailed the growth of natural gas-fired generation.

The drawbacks of solar power have been evident in the past week as temperatures soared daily above 100 degrees Fahrenheit and air-conditioner use leapt in the late afternoon and early evening - just as the sun set. Neighboring states, usually a reliable source of electricity imports, had little left to sell as they slogged through the same heatwave, said officials at the California Independent System Operator (ISO), which manages the state's grid.

"The load forecasts reflect the realities of climate change. It's getting hotter," Steve Berberich, California ISO's chief executive, told its board at a meeting on Monday. "Unfortunately, it is near certain that we'll be forced to ask the utilities to cut off power to millions today to balance supply and demand - today and tomorrow, and perhaps beyond."

Mr. Berberich said his agency had warned the California Public Utility Commission for years of inadequate power during times of maximum demand. "The situation we are in could have been avoided," he said.

At the risk of mixing our avian metaphors, the chickens have now come home to roost. We remain hopeful that those in power in that great state will take this looming catastrophe to heart and change their anti-natural gas policies.

We can only hope that more and more Californians will tire of suffering at the hands of misguided decisions and that they will demand policies that take advantage of clean, abundant and affordable natural gas to work together with renewables to provide adequate supplies of electricity when the sun goes down, the wind dies and the temperatures rise.

We also hope other states learn from California's mistakes and protect their citizens from the dangers to comfort, health and family budgets that result from energy policies that preclude natural gas from a prominent role in powering their grids.