Fog and violent winds

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Fog and strong winds: the speed to adopt, the lighting required by law and the safety distances you need to extend.

Cover, Fog and violent winds

Lesson objectives

Master the use of front and rear anti-fog lights according to weather conditions Adapt your driving and visibility in case of fog or violent wind Know the rules for switching on lights depending on visibility and weather conditions

Fog: a major hazard

Fog involves two thresholds , and confusing them is the most common mistake: as soon as you can no longer see clearly up to approximately 200 metres , dipped headlights at the front and red lights at the rear become mandatory, day and night (art. 30 ); below 100 metres , the obligation to switch on rear fog lights is added (art. 30.1, 2°). Fog that allows visibility of 150 metres therefore already requires dipped headlights, but not yet rear fog lights.

Road in dense fog with reduced visibility

Fog lights: when and how to use them

There are two types of fog lights: front lights and rear lights. Their rules of use are different and precise.

Front fog light

Optional light (not mandatory on all vehicles) that can be switched on only in case of fog, snow or heavy rain. It can replace or accompany dipped headlights.

Rear fog light

Rear fog light: when the vehicle is equipped with it, its use is mandatory in case of fog or snow reducing visibility to less than approximately 100 m, as well as in case of heavy rain, without visibility condition. "These lights may not be used in other circumstances" (art. 30.1, 2°). The obligation to equip, however, falls under technical regulations and not the highway code.

Rear fog lights: switching on rules

Weather condition Visibility threshold Rear light mandatory? Fog Less than 100 m Yes Snow fall Less than 100 m Yes Heavy rain No threshold Yes, always

Frequent exam trap: In case of heavy rain , the rear fog light must ALWAYS be switched on, without visibility distance condition. It is not "if visibility is reduced", it is systematic.

Front fog lights: limited use

Front fog lights are never mandatory: the code merely limits their use. Article 30.1, 1°: they may only be used in case of fog, snow or heavy rain , and they can then replace dipped or main beam lights, or be switched on simultaneously with them. Outside these three situations, including on clear nights, where the temptation is great, switching them on is an offence.

Remember to switch off your fog lights as soon as conditions improve. Prolonged use in clear weather is an offence.

Fog and tunnels: watch out for the change

When entering a tunnel , the weather situation changes suddenly: inside, it does not rain and it does not snow. fog lights, front and rear, must be switched off , the condition that authorised them has disappeared, and article 30.1, 2° prohibits rear fog lights "in other circumstances"; dipped headlights remain on : in a tunnel, visibility and lighting justify the application of article 30. This is exactly what the exam bank tests: in heavy rain, at the entrance to a tunnel, the expected answer is " dipped headlights ", and them alone.

Tunnel entrance with reduced visibility

Dipped headlights: obligation in case of poor visibility

Day and night, the trigger is the same and it does not depend on any particular weather: the inability to see clearly up to a distance of approximately 200 metres (art. 30). Rain, fog, snow, smoke, dust or twilight, it is the visibility distance that commands, and the obligation applies to both front lights and rear red lights .

Dipped headlights: when to switch them on

Situation Dipped headlights mandatory? At night (dusk to dawn) Yes During the day, visibility Yes During the day, normal conditions No

Violent winds: adapt your driving

Lateral wind

Wind gusts coming from the side that can destabilise your vehicle, particularly if you are towing a trailer or driving a tall or light vehicle.

A37

A37, Lateral wind. Gusts coming from the side can destabilise your vehicle, especially if you are towing a trailer, if you are riding a motorcycle, driving a van or a heavy goods vehicle. Hold the steering wheel firmly and anticipate wind gusts near bridges and open spaces.

In case of violent wind, maintain a firm grip on the steering wheel, reduce your speed and increase your safety distance. Lateral gusts can suddenly push you off your trajectory.

Driving in fog: essential precautions

Reduce your speed well before entering a bank of fog Switch on your lights (dipped headlights and rear fog light if visibility Increase the safety distance with the vehicle in front of you Avoid sudden manoeuvres (overtaking, lane change) Be vigilant : fog can be patchy and hide obstacles

If the fog becomes too dense and you cannot see 100 m ahead of you, consider stopping in a safe place (rest area, car park) rather than continuing to risk an accident.

Summary of key points

Dipped headlights : mandatory between dusk and dawn, and as soon as visibility drops below 200 m , even during the day. With red rear lights . Rear fog light : mandatory below 100 m visibility in fog or snow, and in heavy rain without visibility conditions. Prohibited in other circumstances. Front fog lights : never mandatory; usable only in fog, snow or heavy rain. Tunnel : turn off fog lights, keep dipped headlights on. Crosswind (A37) : grip the steering wheel firmly, slow down, increase distances; be cautious when exiting bridges, trenches and overtaken truck convoys. If the fog is too dense, stopping in a safe place is a decision, not a surrender.

Congratulations!

First complete the quiz for this lesson to validate your learning, then practice on the exam simulator and multiple choice questions . You have completed this entire course. Congratulations, time for practice!

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