The game at Grace Road was due to get under way at 18:30 BST.
But umpires Russell Evans and Rob Bailey ruled the ground was unfit for play after a late-morning inspection.
The two clubs were also hit by the weather on Wednesday when their One-Day Cup match at New Road was rained off.
A statement on the club website said: "Aylestone was affected by flash flooding on Tuesday and the Fischer County Ground resembled a lake with the water subsequently gathering in the far corner of the ground.
"Further rain has fallen either side of that particular deluge and although the club brought in heaters to try to dry everywhere out, conditions remain sodden and unfit."
Worcestershire will have Moeen Ali available for Saturday afternoon's home T20 Blast game against Nottinghamshire, for whom fellow England Test player Alex Hales is scheduled to appear.
"It's good when you've got England players playing," said Worcestershire director of cricket Steve Rhodes. "It is a big bonus having Mo available.
"It is a sensible thing to do by the ECB. They want our Blast tournament to have good exposure and become a really good domestic tournament.
"Just as in the Caribbean Premier League, Big Bash and IPL, a lot of the home international players play in those tournaments."
Worcestershire will give fitness tests to skipper Daryl Mitchell and paceman Matt Henry, who have both been sidelined with rib injuries.
Friday's T20 Blast match between Leicestershire and Worcestershire was called off almost seven hours before the scheduled start after heavy rain left the outfield "resembling a lake".