What lights should you use when driving in fog?

When driving in fog, it is important to use low beam headlights. Low beams are designed to provide adequate illumination without causing excessive glare that can reflect off the fog, rain, or snow, which can impede visibility. High beam headlights create a bright light that is easily scattered by fog or precipitation, leading to a dangerous situation where visibility is reduced instead of improved.

Fog lights, if used, are supplemental and work best close to the road surface, reducing the amount of light that is interfered with by fog. However, they should be used in conjunction with low beam headlights, as low beams provide necessary forward and side illumination for better visibility of roadway signs and other vehicles. Turn signal lights serve a different purpose, indicating to other drivers your intentions to change direction, and are not meant for improving overall visibility in foggy conditions. Thus, using low beam headlights is the most effective choice for safe driving in fog.