York Regional Police say they were called to the parking lot of the Vaughan Mills shopping mall shortly after 2 p.m. on Sunday.
According to police, the infant was sleeping in the back seat. The van's windows had been left down about an inch. The temperature outside was more than 30 C, police say.
A window was forced down and responding officers say the child was showing "obvious signs of exposure to high heat," which included reddened skin and hair that was drenched in sweat.
The child's father showed up about a half-hour after police were called. The 42-year-old Toronto man has been charged with leaving a child unattended under the Child and Family Services Act.
The child was released into the custody of her mother, after being taken to hospital as a precaution.
Police are reminding the public not to leave children or pets unattended in vehicles.