Tropical Storm Oscar doused Cuba on Monday, three days after a massive power failure plunged more than 10 million people into the dark as the island worked to restore its decades-old power grid.

"Some additional weakening is likely while Oscar moves across the mountainous terrain of eastern Cuba, but Oscar is forecast to be a tropical storm when it moves north of Cuba late today and then moves near the southeastern and central Bahamas on Tuesday," the hurricane center said Monday morning.

Cuba has had four electric grid collapses since Friday, and most of the country remains in the dark as slow progress is made to restore power.