• Tune in to your radio to stay informed of approaching storms.
• If you see a tornado or hear a tornado warning, don't try to outrun it.
• Turn on your headlights (low beams) and slow down. Many states require the use of headlights during rain.
• Allow extra distance for braking.
• Do not drive unless necessary.
• Pull safely onto the shoulder of the road away from any trees that could fall on the vehicle.
• If at all possible, pull into a sturdy garage, parking garage, or under a shelter to minimize hail damage.
• Stay in the car and turn on the emergency flashers until the heavy rains subside.
• Avoid downed power lines.
• Approach intersections with caution
• Treat traffic lights at intersections as stop signs
• After the storm, thoroughly evaluate your vehicle for damage.
• If you find glass damage, carefully remove any glass from the interior of your vehicle, and cover the damaged area to prevent further water damage to your interior.

Treat Hail storms in much the same way you would handle a thunderstorm.

Sources: FEMA.gov, NOAA.gov