Headlights, night driving and bad weather

Key points

1. Headlights must be on from 30 minutes after sunset until 30 minutes before sunrise.

   Source: Handbook p. 45

   “Your car headlights must be turned on 30 minutes after sunset until 30 minutes before sunrise.”
   Tennessee Comprehensive Driver License Manual, Handbook p. 45

2. Headlights are also required when rain, mist or snow requires constant use of your wipers.

   Source: Handbook p. 45

   “When rain, mist, snow, or other precipitation requires constant use of windshield wipers.”
   Tennessee Comprehensive Driver License Manual, Handbook p. 45

3. Dim your high beams when an oncoming vehicle is within 500 feet or when following within 500 feet.

   Source: Handbook p. 45

   “you must dim or lower the beam when an oncoming vehicle is within 500 feet (approximately the distance of one city block) or when you are following another vehicle within 500 feet.”
   Tennessee Comprehensive Driver License Manual, Handbook p. 45

4. Driving with only parking lights when visibility is limited is unsafe and against the law.

   Source: Handbook p. 45

   “When there is limited visibility, the use of parking lights alone is not only unsafe, it is against the law.”
   Tennessee Comprehensive Driver License Manual, Handbook p. 45

5. The basic rule for night driving is never outrun your headlights.

   Source: Handbook p. 74

   “The basic rule for safe night driving is this: NEVER OUTRUN YOUR HEADLIGHTS.”
   Tennessee Comprehensive Driver License Manual, Handbook p. 74

6. The pavement is especially treacherous when rain first begins, as dirt and oil mix with the water into a greasy film.

   Source: Handbook p. 75

   “The pavement is particularly treacherous when it first begins to rain. Accumulations of dirt and oil will mix with the water, and create a greasy film on the roadway.”
   Tennessee Comprehensive Driver License Manual, Handbook p. 75

7. In daytime fog, heavy rain or snow, turn on low beams; it is Tennessee law.

   Source: Handbook p. 75

   “WHEN DRIVING THROUGH DENSE FOG, HEAVY RAIN OR SNOW DURING THE DAYTIME, TURN ON YOU LOW BEAM HEADLIGHTS. This gives you better visibility and alerts oncoming cars to your presence, it is also a requirement of Tennessee law.”
   Tennessee Comprehensive Driver License Manual, Handbook p. 75

8. If you start to hydroplane, slow down gradually by letting up on the gas.

   Source: Handbook p. 76

   “If you vehicle starts to hydroplane, slow down gradually by letting up on the gas.”
   Tennessee Comprehensive Driver License Manual, Handbook p. 76

9. In a skid, stay off the brake and steer the way you want the car to go.

   Source: Handbook p. 76

   “Stay off the brake. Until the vehicle slows, your brakes will not work and could cause you to skid more. b. Steer. Turn the steering wheel in the direction you want your car to go.”
   Tennessee Comprehensive Driver License Manual, Handbook p. 76

10. Most cars can be swept away in 18 to 24 inches of moving water.

    Source: Handbook p. 76

    “In fact, most cars can be swept away in 18 to 24 inches of moving water.”
    Tennessee Comprehensive Driver License Manual, Handbook p. 76

Numbers to know

Recognize these signs

3 questions from the Tennessee practice test

1. 1. When constant windshield-wiper use is required by rain or other precipitation, what lighting rule applies?

   1. Parking lights alone are sufficient
   2. Headlights must be turned on
   3. Headlights are required only after sunset
   4. Hazard flashers replace the headlight requirement
   Show answer

   Headlights must be turned on. Tennessee requires headlights when rain, mist, snow, or other precipitation makes constant windshield-wiper use necessary. The rule does not depend on whether the driver personally thinks visibility remains adequate, and parking lights alone are not a substitute. Waiting until sunset ignores the daylight inclement-weather provision. Hazard flashers serve a different warning purpose. Tie the requirement to the wipers: if precipitation demands their constant use, turn on the headlights so the vehicle is easier for others to see.

2. 2. Which headlight beam should you use if you must drive through fog?

   1. Low beams
   2. High beams
   3. Parking lights alone
   4. Auxiliary fog lights alone
   Show answer

   Low beams. Use low-beam headlights in fog. High beams reflect light back toward your eyes and impair visibility, so more intense forward light is not automatically better. Parking lights or fog lights alone are not acceptable substitutes. The cue is the moisture obscuring the road: select the beam that lights the road without the stronger reflection, reduce speed and keep the windshield clear as needed.

3. 3. What does it mean to avoid outrunning your headlights at night?

   1. Drive slowly enough to stop within the distance you can see
   2. Keep speed equal to the daytime maximum
   3. Watch only the brightest part of the beam
   4. Maintain daytime speed whenever high beams are on
   Show answer

   Drive slowly enough to stop within the distance you can see. At night, keep stopping distance shorter than the distance you can see. The headlights limit how early an object becomes visible, so a daytime speed may leave too little room to stop. High beams do not remove the need to judge that room. Adjust speed to the light, road and weather conditions so a pedestrian, animal or object can be seen before it is too late to stop.

Source: the Tennessee Comprehensive Driver License Manual, Section B-6: Driving at Night and in Inclement Weather Conditions. This lesson is a plain English summary, not the law itself; where it differs, the manual and the statute govern. Last checked 2026-09-27.