Referee Leighton Hodges said he had no choice but to call off last night's Pro12 clash between Ulster and Scarlets at Ravenhill.
The Welsh official inspected the ground at 3.0 and when the situation deteriorated an hour later he made the decision to postpone the match.
"Large parts of the pitch were under water and the safety of the players would be affected if we went ahead with the game.
"There was just no let-up in the rain and it just didn't give the groundsmen any chance to deal with the surface water.
"From my point of view, the safety of the players is paramount and there was no choice but to call off the game," he said.
Ulster Rugby said that tickets purchased for the game would be valid for the rescheduled fixture.
The game is now likely to be played in March, with either Friday 7 or Friday 14 the possible dates.