The American missed Sunday’s loss at Newcastle with the injury suffered against Stoke on Boxing Day, and is now set to miss out until well into 2015.
“Tim Howard will be out between five and six weeks with a calf injury,” Martinez said at his press conference ahead of the New Year’s Day game against Hull.
Joel Robles, who was with Martinez at Wigan, is deputising and, while the Toffees boss is happy with him, he may look to bring in another stopper.
“I thought Joel was very calm against Stoke and did well against Newcastle. But we will assess whether we need cover,” the Spaniard added.