PARIS — Not so much the French Open as the French closed.

For the first time in 16 years, unrelenting rain Monday washed out a full day of play at the only Grand Slam tennis venue without a retractable roof over its show court, clogging the schedule with unfinished and postponed matches and prompting the frustrated tournament director to plead – again – for a roof as soon as possible.

“Our roof is a necessity,” Guy Forget said, as players were sent back to their hotels and thousands of would-be spectators told to apply for refunds for their unused tickets.

“I’m a bit annoyed today, to say the least.”

Chopped and changed plans to modernize Roland Garros now call for a retractable roof by 2020 over Court Philippe Chatrier, as part of a modernization of the cramped clay-court venue. But opposition and legal action from local residents and environmental activists has slowed the ambitious project, which would expand Roland Garros into botanical gardens next door.

With damp spectators sheltering where they could from the downpours and no letup forecast, tournament organizers announced in the early afternoon that there would be no play at all for the first time since May 30, 2000.

“We knew today was going to be horrible and it went beyond what we had imagined. That’s why we sent back the players so early,” Forget said.

If the weather breaks Tuesday, matches will start three hours earlier than initially planned and be spread over more courts.