The looming bad weather threatens to further damage the 850-year-old cathedral whose roof was destroyed by the April 15 blaze, leaving the church to the mercy of the elements.
Architect-in-chief Philippe Villeneuve said he had to rush the installation of the protective covers that started Tuesday.
"The climbers, since it will be climbers who will do that, and the scaffolders, are ready," Villeneuve told BFMTV on Tuesday. "The beams are there, the tarpaulin on its way .... The highest priority is to protect the cathedral from the rain to come."
Some of Notre Dame's remaining statues were removed by crane before the tarpaulins were hoisted up. Workers in the afternoon began dragging them over to cover vulnerable parts of the structure.
Parts of the cathedral, including its partially-destroyed vaulted ceiling, had already been soaked with water after firefighters desperately fought the blaze for over 12 hours that day.
Notre Dame's vaulted ceiling was also badly damaged after the cathedral's 19th-century spire burnt up and collapsed.
Notre Dame isn't expected to reopen to the public for five or six years, according to its rector, although French President Emmanuel Macron is pushing for a quick reconstruction.
So far, investigators think the devastating fire was an accident, possibly linked to the cathedral's renovation work.
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