Rain, fog and night driving

Key points

1. When rain first starts, reduce speed and allow at least twice the normal following distance.

   Source: Handbook p. 75

   “You should reduce speed, use extra caution, and allow at least twice the normal following distance.”
   Hawaii Driver's Manual, Handbook p. 75

2. Partial hydroplaning may start at 35 miles per hour.

   Source: Handbook p. 75

   “Partial hydroplaning may start at 35 miles per hour (56 km/h).”
   Hawaii Driver's Manual, Handbook p. 75

3. Hydroplaning increases with speed and with the amount of water on the road.

   Source: Handbook p. 75

   “The extent of hydroplaning increases with speed and with the amount of water on the highway.”
   Hawaii Driver's Manual, Handbook p. 75

4. At 55 miles per hour in heavy rain, tires may lose all contact with the pavement.

   Source: Handbook p. 75

   “At 55 miles per hour (89 km/h) in a heavy rain the tires may lose all contact with the pavement.”
   Hawaii Driver's Manual, Handbook p. 75

5. After driving through deep water, reduce speed and press the brake gently until the brakes work again.

   Source: Handbook p. 76

   “Reduce speed and apply gentle pressure on the brake pedal until your brakes work properly again.”
   Hawaii Driver's Manual, Handbook p. 76

6. Never drive through swiftly moving water over 1 foot deep.

   Source: Handbook p. 76

   “Never drive through a flooded area where water over one foot deep (30 cm) is moving swiftly.”
   Hawaii Driver's Manual, Handbook p. 76

7. In fog, if you cannot see at least 40 feet, pull completely off the pavement and stop.

   Source: Handbook p. 76

   “If you are unable to see at least two car lengths (40 feet or 12 meters), pull completely off the pavement and stop.”
   Hawaii Driver's Manual, Handbook p. 76

8. At night, drive slowly enough to stop within the distance you can see ahead.

   Source: Handbook p. 77

   “Reduce your speed so that you can stop within the distance you can see ahead.”
   Hawaii Driver's Manual, Handbook p. 77

9. Red lane marking reflectors mean you are going the wrong way.

   Source: Handbook p. 77

   “Recognize that red lane marking reflectors mean you are going the wrong direction in the traffic lane.”
   Hawaii Driver's Manual, Handbook p. 77

Numbers to know

3 questions from the Hawaii practice test

1. 1. At about what speed may partial hydroplaning begin?

   1. 15 miles per hour
   2. 25 miles per hour
   3. 65 miles per hour
   4. 35 miles per hour
   Show answer

   35 miles per hour. The manual places the possible beginning of partial hydroplaning at 35 miles per hour, with the extent increasing as speed and standing water increase. The lower figures understate the point identified in the text, while 65 miles per hour ignores that loss of contact can develop earlier. Hydroplaning removes braking, steering, and acceleration control, so reduce speed before water accumulates. Check tire tread and inflation too, since worn or underinflated tires can hydroplane at lower speeds.

2. 2. At what speed in heavy rain may tires lose all contact with the pavement, according to the Hawaii manual?

   1. 20 miles per hour
   2. 100 miles per hour
   3. Tires never fully lose contact
   4. 55 miles per hour
   Show answer

   55 miles per hour. Up to about 35 mph good tread wipes the road like a windshield wiper, partial hydroplaning may start at 35 mph, and at 55 mph in a heavy rain the tires may lose all contact with the pavement, leaving you unable to brake, accelerate or turn. Prevent it with good tread depth, proper inflation and reduced speed on wet roads.

3. 3. When the first drops of rain make the road slick, what following distance should a driver allow?

   1. At least twice the normal following distance
   2. Exactly the normal following distance
   3. Half the normal following distance
   4. No following distance if headlights are on
   Show answer

   At least twice the normal following distance. The first rain can leave oil and water on the pavement, making the surface especially slippery. The manual pairs reduced speed and extra caution with at least twice the normal following distance. Keeping the ordinary gap does not account for the changed stopping conditions, and shortening it makes a sudden stop more dangerous. Headlights improve visibility to others but do not restore tire grip. When rain begins, lift off the pace, enlarge the gap, and expect the road to be slick before it looks flooded.

Source: the Hawaii Driver's Manual, Chapter X: Safe Driving Techniques. 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.