West Virginia State Code 17C-15-46 clearly and thoroughly outlines the rules regarding child safety seats.

Because people always want to know how big their child must be to stop using a booster:

• Children under the age of eight and shorter than four feet nine inches tall must be in an approved child safety seat if the vehicle is in motion.
• Violators can be fined between $10-$20.

Note that this code does not apply to operated-for-hire vehicles.

Unattended Children and Pets

Leaving children or pets unattended in vehicles is dangerous for a variety of reasons. It can kill or injure (especially in hot or cold weather) and it may be illegal in your municipality. It also puts them at risk for kidnapping (or petnapping), and curious children may be tempted to push pedals or turn keys.

The best, point blank advice is to just never leave your child or pet unattended in a vehicle, regardless of the climate, the neighborhood, or whether you took the keys with you.