Cuba's efforts to restore electricity after a series of blackouts were hampered again on Monday when a second nationwide power cut in a day, the sixth this year, struck its national grid.

Power began returning to parts of Havana and several provinces in central and western Cuba during Monday and, by midday, authorities said about half of the capital had electricity again.

However, the state electricity provider later warned that unfavorable weather had again interrupted the restoration process.

Cuba blackouts: What have authorities said?

"In the process of reestablishing the [National Electric System], existing weather events caused disruptions to the grid, directly affecting the generator units that were online," the provider said in a statement posted to social media on Monday afternoon, without specifying the extent of damage or how many areas were affected.