Staying safe on the road in fog
Slow down and keep your distance
Oct 07, 2026- Poor visibility pushes both drivers and technology to their limits
- Don’t rely on automatic headlights
- Emergency braking assist helps, but doesn’t replace your own caution
Fall marks the start of fog season – and that’s when vehicle technology and drivers regularly reach their limits. DEKRA accident researcher Luis Ancona: “Visibility while driving can decrease very quickly, while at the same time contrasts are lost and judging distances becomes more difficult. Critical situations can arise all too easily.” Caution and an adapted driving style are therefore essential.
Even modern vehicle technology does not offer complete safety in fog. “Emergency braking assist, for example, can provide support in critical situations but is no guarantee against rear-end collisions – especially if you’re driving too fast or not maintaining the necessary distance”, says Ancona. Fog can also impair cameras and sensors and temporarily disable certain system functions. It remains the driver’s responsibility to adjust distance and speed to visibility conditions.
Daytime Running Lights: Taillights Usually Not Active
The same applies to lighting. When visibility is significantly impaired by fog, snowfall, or rain, drivers should use low beams even during the day. “The automatic headlight system cannot always detect foggy conditions, however. This often results in the vehicle continuing to drive with only daytime running lights on”, says Ancona. In such cases, the headlights do not provide the necessary brightness – because daytime running lights are designed solely to make the vehicle more visible to others during daylight hours. In addition, the taillights are often turned off – which poses an extreme risk of accidents in fog. It is important to manually switch the headlight switch from the “AUTO” position to low beams.
The same applies to lighting. When visibility is significantly impaired by fog, snowfall, or rain, drivers should use low beams even during the day. “The automatic headlight system cannot always detect foggy conditions, however. This often results in the vehicle continuing to drive with only daytime running lights on”, says Ancona. In such cases, the headlights do not provide the necessary brightness – because daytime running lights are designed solely to make the vehicle more visible to others during daylight hours. In addition, the taillights are often turned off – which poses an extreme risk of accidents in fog. It is important to manually switch the headlight switch from the “AUTO” position to low beams.
Adjust your speed to visibility conditions
Equally important is adapting your driving style. Sudden fog banks are particularly critical. In such cases, you should reduce your speed early and brake in a controlled manner. “The key is to drive at a speed that allows you to come to a stop within the distance you can actually see”, says Ancona.
Equally important is adapting your driving style. Sudden fog banks are particularly critical. In such cases, you should reduce your speed early and brake in a controlled manner. “The key is to drive at a speed that allows you to come to a stop within the distance you can actually see”, says Ancona.
A common mistake in foggy conditions is to rely too heavily on the vehicle ahead. “Blindly trusting the taillights of the vehicle in front is risky; this, too, regularly leads to rear-end collisions. Often, all it takes to trigger one is a sudden braking maneuver further ahead,” explains the accident researcher.
Drivers who turn on their high beams in fog hope for better visibility but end up with the opposite result. “This is due to the strong scattering of light by the fog droplets,” says Ancona. “The scattered light can create a bright haze in front of your eyes and further reduce the contrast of the surroundings.”
Turn on fog lights when visibility is poor
In these weather conditions, fog lights – which are mounted low and illuminate the road surface broadly and evenly – are in their element. They improve the illumination of the area immediately in front of the vehicle, even in thick fog.
In these weather conditions, fog lights – which are mounted low and illuminate the road surface broadly and evenly – are in their element. They improve the illumination of the area immediately in front of the vehicle, even in thick fog.
The rear fog light should only be turned on when visibility is less than 50 meters. As soon as visibility improves again, the high-intensity light must be turned off so as not to dazzle others.
In addition to a fully functional lighting system, the DEKRA accident researcher also recommends clean windows inside and out, as well as intact windshield wipers for safe driving in fog.