Cuba's electrical grid collapsed again on Sunday, the fourth such failure in 48 hours, with a hurricane making landfall to compound the island's misery and threaten further havoc on its infrastructure.

Cuba earlier on Sunday had said it was making headway restoring service after multiple false starts, though millions of people remained without electricity more than two days after the grid's initial collapse.

"Restoration work began immediately," the country's energy and mines ministry said on X.

Hurricane Oscar made landfall on the Caribbean island on Sunday, bringing strong winds, a powerful storm surge and rain to parts of eastern Cuba and threatening to further complicate the government's efforts to reestablish service.

Cuba's meteorological survey warned of "an extremely dangerous situation" in eastern Cuba, while the US National Hurricane Center reported winds of 120 kilometres per hour as the storm made its way across the island.

"On the forecast track, the center of Oscar is expected to continue moving across eastern Cuba tonight and Monday, then emerge off the northern coast of Cuba late Monday and cross the central Bahamas on Tuesday," the Hurricane Center said.

The government canceled school through Wednesday – a near unprecedented move in Cuba – citing the hurricane and the ongoing energy crisis. Officials said only essential workers should report to work on Monday.

The repeated grid collapses marked a major setback in the government's efforts to quickly restore power to exhausted residents already suffering from severe shortages of food, medicine and fuel.

The multiple setbacks in the first 48 hours also underscored the complexity of the work and the still precarious state of the country's grid.

Cuba had restored power to 160,000 clients in Havana just prior to the grid's Sunday collapse, giving some residents a glimmer of hope.

But housewife Anabel Gonzalez, of old Havana, a neighborhood popular with tourists, said she was growing desperate after three days without power.

"My cell phone is dead and look at my refrigerator. The little that I had has all gone to waste," she said, pointing to bare shelves in her two-room home.

Energy and mines minister Vicente de la O Levy told reporters earlier on Sunday he expected the grid to be fully functional by Monday or Tuesday but warned residents not to expect dramatic improvements.

It was not immediately clear how much the latest setback would delay the government's efforts.

Cuba's national electrical grid first crashed around midday on Friday after the island's largest power plant shut down, sowing chaos.

The grid collapsed again on Saturday morning, state-run media reported

By early evening on Saturday, authorities reported some progress restoring power before announcing another partial grid collapse. (Reuters)