McDonald's all-day breakfast may debut nationwide by October

McMuffins for late risers
McMuffins for late risers

Just months after McDonald's began testing all-day breakfast at some of its restaurants, the fast food giant could begin offering it nationwide in October, according to a memo sent to domestic franchisees and employees, a source confirms for CNBC.

The company recently began testing all-day breakfast in in Nashville, Tennessee, following another test in the San Diego, California, region.

McDonald's has long maintained that serving all-day breakfast would be too difficult operationally to implement, thanks to limited grill space.

The memo advises franchisees to be ready for all-day breakfast to launch as soon as October.

"Serving all-day breakfast is likely the number one request we hear from McDonald's customers," according to a statement from McDonald's. "We're testing it out in a few markets to learn more about this possibility. We know your mouth is watering, but there's no news on this yet."

The Wall Street Journal first reported the news.