The St Andrews pitch had reportedly been given the all clear, but conditions around the ground and on roads in the area forced an postponement of the Premier League tie.
Referee Mike Jones said: “I spoke to the safety officer. The roads and surrounding areas in Birmingham are not very good.
“You’ve got a crowd of 20,000-plus coming today. Major accidents could potentially occur in and around the stadium so it’s a joint decision between myself and the head of safety at Birmingham City.
“At 10.30am this morning (Saturday) everything was looking good. I had communication with the club, the pitch was in fine condition and the undersoil heating was on.
“There was nothing at all they could have done, it was out of their control.”
