"The first year of 5G for the iPhone will be a disappointment for investors," Munster said on "Squawk Alley." And he blames the carriers for the delay.
"Ultimately, this is a massive opportunity for Apple, huge play on 5G, but it's going to take a while for networks to roll out coverage."
5G is a next-generation mobile network that promises faster data speeds, lower latency and other capabilities to support emerging technologies such as self-driving cars. Coverage in the U.S. is not yet widespread, but expectations are high for increased coverage in 2020. Verizon CEO Hans Vestberg has said he expects half the U.S. to be covered by 5G in 2020.
Some smartphone makers such as Samsung have already released phones that support 5G, but Apple is not expected to release its first 5G iPhone until next year.
Many analysts expect that a 5G iPhone will reignite slumping phone sales that have transpired in recent years as users hold onto their older models longer. One report suggests the tech giant may ship more than 80 million units.
Indeed, current iPhone users seem interested in a 5G model, according to a recent Piper Jaffray survey. Of the 1,050 current iPhone owners who responded, 23% said they would upgrade to a $1,200 5G iPhone, up from 18% of participants a few months earlier.
But Munster is skeptical that the carriers will be able to achieve the coverage they've promised, which could suppress sales.
Disappointing sales would rest "largely on the shoulders of the carriers who have talked a lot about the 75% coverage by the end of next year. I think that that is optimistic at the best case," he said.
Shares of Apple have risen about 80% year-to-date, and they touched a 52-week high of $246.25 during Friday trading as President Donald Trump announced tariffs set for Sunday that would've hit Apple's core products had been canceled.
Munster said he believes Apple will continue to rally into the new year, even with his less-than-rosy outlook on 5G iPhone sales.
"I think that this is going to be one of the best performers, if not the top tech performer next year as well," Munster said, arguing it could reach the $350 to $400 range.