Referee Lee Evans ruled it was impossible to see all four corners flags from every area of the pitch and the game was postponed at 6.45pm.
The clubs have arranged to stage the fixture on Tuesday 7 December (7.45pm).
In the meantime, the Saints are next in action at Neath on Wednesday night, while Llanelli are at home to Haverfordwest next Saturday.
Photo: A fog-shrouded Park Hall tonight.