A Long Island man with a history of drug arrests left his baby boy to die inside a parked car where the temperature reached at least 119 degrees, cops said yesterday.

Devon Fenner, 25, was also found with a “misdemeanor” amount of marijuana after the incident on Tuesday in Hempstead, and cops said they’re investigating whether he was high at the time.

Fenner told detectives he forgot to take 7-month-old son Dominick out of the 2003 Toyota after dropping off his girlfriend at work and taking two other kids they’re raising to day care.

Fenner claimed the baby was in the car for only about 30 minutes, but cops didn’t get a 911 call reporting that the boy wasn’t breathing until about 1:40 p.m., according to Nassau County cops Department.

Cops and EMTs tried to revive the child using CPR, but he was pronounced dead less than an hour later at Mercy Medical Center in Rockville Centre.

Nassau Police Inspector Kenneth Lack said an autopsy results were pending, but that the boy’s death was “possibly” due to the heat inside the vehicle.

“I believe one window was cracked, but unfortunately, cracking a window on a 90-degree day doesn’t do much,” Inspector Kenneth Lack said during a news conference.

Fenner, who was charged with criminally negligent homicide, has five prior arrests since 2004 on charges including possession of marijuana, possession of a gun and trespassing. He was released on $50,00 bond after pleading not guilty at his arraignment yesterday.

He and several relatives refused to comment.

In addition to the dead boy, Fenner is the father of two other sons, ages 7 and 8, with his girlfriend and another woman, respectively.

The two youngest boys were being raised by Fenner and his girlfriend, along with her 4-year-old daughter from another relationship.

Fenner’s Facebook page, with the user name NUM1GANGSTER05, boasts “(Ladiesluvme)” under his real name and features a picture of him flipping the bird.