It is illegal to leave a child age six or younger unattended in a vehicle on a hot day:

Question

It is never a good idea to leave a child unattended in a car. It is illegal to leave a child age six or younger unattended in a vehicle. A child may be left under the supervision of a person age 12 or older.

Accepted Answer

Even if they are secured in a child passenger restraint system.

Answer

If they are supervised by a person twelve years of age or older.

Answer

Only if the key is in the ignition.