The boy's sister was also in the trailer.
A 25-year-old Florida man was charged after allegedly leaving his 8-month-old baby in a trailer with no air conditioner, police said.
William Francis Hendrickson's baby, William Francis Hendrickson IV, was found dead in their Largo trailer on Thursday after police arrived to do a welfare check.
Read: Mother Gives Birth in Restaurant Bathroom, Grandma Helps Stash Baby in Trash: Cops
The temperature in the trailer was 109 degrees when officers arrived.
The baby's body temperature was reportedly 105.6 degrees when he was found inside of a playpen in the mobile home's bedroom. Paramedics were unable to revive the baby boy.
The boy's two-year-old sister, who was also in the trailer, suffered from dehydration and was hospitalized.
The children's mother, Elizabeth Michelle Rutenbeck, was reportedly arrested the week before and is being held in jail on battery charges after allegedly fighting with Hendrickson's mother.
Child services told the Hendrickson not to leave the children in the bedroom the day before the boy's death, but he told authorities he had "nowhere else to go" after his girlfriend was arrested, TampaBayTimes reported.
Read: Baby Dies From Meningitis After Deadly Kiss: 'Don't Let Anyone Kiss Your Baby'
Hendrickson was charged with aggravated manslaughter and child neglect.
He is being held on $150,000 bond.
Watch: 1-Month-Old Baby Girl Dies After Falling Down Malfunctioning Elevator Shaft
