Griffiths netted his first league hat-trick at the weekend in Celtic's 5-0 demolition of Inverness, having signed for the Glasgow giants from Wolves in January.
And McGhee is certain the 23-year-old, who could win his fifth cap in Poland on Wednesday, will be a key figure in the qualification campaign that gets under way in Germany in September.
"There are a fairly limited number of players that we feel are going to be good enough to qualify us," he said. "Leigh Griffiths is one of them.
"And we think that with Leigh Griffiths being at Celtic now, and the new experience he will have next year of the Champions League and all that, can only make him a better player.
"And it can only make him more prepared and more effective for the national team.
"We'd expect him to get a lot of goals between now and the end of the season and then it will be about the start to the (new) season.
"The group of strikers we'll have to choose from, maybe even (Craig) Mackail-Smith will be fit by then, and you've got Ross McCormack, you've got Steven Fletcher, Leigh Griffiths, Jordan Rhodes, so you've got all this group who'll all be vying.
"It's not about who is playing well now and who is scoring hat-tricks for Celtic today, it's going to be about August, September, the start of the season and how they are looking then."
