Munster predicted sales will be "down 15 percent year-over-year and the reason is nothing is wrong with the iPhone.”
The blockbuster iPhone 6 releases in 2014 and 2015, which included the huge Chinese market, helped fuel Apple's record iPhone sales, according to previous earnings reports.
"People typically hold their phones for a couple years so they jumped and bought their phones maybe earlier and it pulled forward the demand," Munster said.
Even Apple has warned of a difficult quarter. During the earnings call for the first fiscal quarter of 2016, which ended Dec. 26, Apple reported sales of 74.8 million iPhones, up less than 1 percent from the same time one year ago.
While the likely decline may be a headline, analyst Munster said it's not a reason to worry for Apple. He predicts iPhone sales will once again increase by the end of this year, following the likely release of a new product in September.