Not sure if his official DOB has ever been mentioned? but I was reading on a “FanDom” page that had his DOB was listed as October 19, 1957. I thought this was cool since the movie is realesed on his birthday 
It might have been mentioned in Halloween 1, I remember they say something about him having to be tried on his 21st birthday, but the trial was pushed into the first week of November. Even if they don’t mention the exact date, the 19th of October sounds reasonable considering the previous information.
It’s mentioned in the opening sequence of Resurrection but that’s it, which is the one posted here.
My best friends birthday is October 19th! Same birthday as Floyd Mayweather Sr., John Favreau, John Lithgow, Desmond Herrington (both on Dexter) and Michael Gambon (Dumbledore)
October 19th, 1957 is indeed correct. The date was confirmed and that year would make him 6 on Halloween night, 1978.
It may have been on that slip of paper in Hoffman’s office in Halloween IV that had his middle initial as M.
Yes, he was born in 1957.
The end credits are wrong.
„Tony Moran - Michael (age 23)“
Actually he‘s 21 in H78.
In Halloween 1978, they cut some footage for TV together, and his name was Michael Audrey Myers. I remember the M. though from what you’re talking about but I don’t think we ever got that full middle name.
Also Judith Myers birthdate on her headstone is wrong. It says November 10, 1947. This would have made her only 15 on October 31, 1963.
I think the OP knows he was born in 1957, she was asking about the day/month. October, 19.