The decision was made following an inspection of the Fratton Park surface by local referee Andy Davies.
He told Pompey's official website: "The pitch was very wet, with standing water in various areas.
"It's barely playable at the moment, but we've also had to take into account the weather forecast, which is pretty dire for the next 24 hours.
"The pitch would therefore be unplayable and it would be dangerous for the players, which is our ultimate concern."
A new date for the fixture will be announced in due course.