Tesla CEO Elon Musk announced Wednesday that the company's "unreal" semi truck was tentatively set to be unveiled in October.

Elon Musk tweet: Tesla Semi truck unveil & test ride tentatively scheduled for Oct 26th in Hawthorne. Worth seeing this beast in person. It's unreal.

Musk has already revealed some details about the project. Speaking at Tesla's annual shareholder meeting in June, the CEO said the automaker has been working with its "biggest customers" on the design of the semi truck, so they already know what the Tesla is making.

"They want to know how many can they buy, and how soon," Musk said at the time. He also said he "really recommend[s]" people show up for the unveiling, adding that "maybe there is a little more than we are saying here."

Musk had earlier said the semi would be unveiled in September.

Elon Musk tweet: Tesla Semi truck unveil set for September. Team has done an amazing job. Seriously next level.

—CNBC's Robert Ferris contributed to this report.