The lights came back on Sunday night in Lidia Núñez Gómez’s Havana neighborhood — the first time since Friday morning — so she rushed to use her electric cooker to save the frozen chicken legs and pork her son had sent her from the United States.

Meat is scarce, the power was sure to go out again soon, and Ms. Núñez, 81, needed to keep food from rotting.

Her daughter, Nilza Valdés Núñez, 61, fury in her voice and tears in her eyes, took stock of months of power outages, plus food and gas shortages.

With a hurricane slamming the eastern coast of the country and a four-day blackout that plunged the entire country into darkness, she summed up the past few days like this: “super bad.”

“The lack of electricity, of gas, and all the other problems we have here,” Ms. Valdés said, pausing to weep, “make you feel bad.”

Cuba, a Communist country long accustomed to shortages of all kinds and spotty electrical service, is in the throes of a crisis so severe that experts say it threatens to explode into social unrest.