More than 300,000 spectators are expected to line the banks of the River Seine when the athletes parade through the heart of Paris on a flotilla of barges and riverboats, part of an extravagant opening ceremony that will be watched by a global audience of billions.
About 25 mm (0.98 inch) to 30 mm (1.18 inches) of rain is expected between 6 pm and midnight on Friday during the 3-hour ceremony attended by world leaders and global celebrities, the equivalent of 15 days of rainfall, weather forecaster Patrick Marliere said.
"It's going to be a disaster for these few hours," Marliere, the head of independent weather forecaster Agate Meteo, said on RMC radio.
"I've been running models for two hours, going full circle, comparing all weather models, but unfortunately everything is confirming this trend for the start and the end of this evening. We won't be able to avoid it," he said.
State weather forecaster Meteo France also expects rain on Friday evening.
"The scenarios of the last few days that had mentioned risks of rainfalls are being confirmed for the end of the day," it says on its website.
The Olympics had an inauspicious start on Friday, after saboteurs struck France's TGV high-speed train network in a series of pre-dawn attacks across the country, causing travel chaos hours ahead of opening ceremony.
