Netherlands keeper Krul missed the team's 1-0 loss at West Ham United on Saturday after sustaining ligament damage in training.
Reserve goalkeeper Rob Elliot deputised for Krul at Upton Park and will continue during a busy December fixture list that features games against Chelsea, Arsenal and Manchester United, as well as the League Cup quarter-final at Tottenham Hotspur.
Speaking at a news conference ahead of Tuesday's Premier League visit to second-bottom Burnley, Pardew said Krul would not return until "January - possibly mid-January".
Krul joins captain Fabricio Coloccini, Daryl Janmaat, Mike Williamson and Massadio Haidara on the sidelines for the visit to Burnley. Moussa Sissoko and Jack Colback are both suspended.
"It's critical in terms of the spine of the team: no Tim (Krul), no Coloccini, no Moussa (Sissoko), no Jack (Colback), who would all start if they were fit," Pardew said.
"But we've been in this position before and we've won because the squad has good strength and I hold no fears going to Burnley."
Defeat at West Ham ended a run of five consecutive league wins for Pardew's men, leaving Newcastle in ninth place but only three points outside the top four with 19 points from 13 games.
Burnley have enjoyed a good run of form too, recording their first wins of the season against Hull City and Stoke City before drawing 1-1 at home to Aston Villa at the weekend.
"They've done terrifically of late and they'll be gunning for us," Pardew said. "We respect them but we don't fear them."
(Reporting by Sam Holden, editing by Ed Osmond)
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