What should I not do when driving in fog?

[GarrettLee]

The most critical rule is to never use your high-beam headlights in fog. The bright light reflects off the water droplets, creating a blinding "white wall" effect that severely reduces your own visibility. Instead, use your vehicle's low-beam headlights, which are designed to cut through fog better by illuminating the road surface without excessive glare. Relying solely on parking lights or fog lights is insufficient for making your vehicle visible to others.

Driving in fog demands a fundamental shift in behavior, primarily centered on reducing speed and increasing following distance. Data from the National Highway Traffic Safety Administration (NHTSA) indicates that over 28,000 crashes annually occur in foggy conditions in the U.S., with a disproportionate number being severe multi-vehicle chain collisions. This high risk is directly tied to drivers failing to adjust their speed to match the severely limited sight distance.

A common and dangerous mistake is maintaining normal highway speeds. If your visibility is down to 100 feet, your speed must allow you to stop within that distance. Sudden stops are a major cause of pile-ups. Increase your following distance to at least 5-6 seconds behind the vehicle ahead, giving yourself a crucial buffer to react to unseen hazards.

Do not use the tail lights of the car in front as your only guide. This "target fixation" can lead to following them too closely and ignoring other road cues. If you cannot see the road's edge, use the right-side line as a guide, not the center line, to avoid drifting into oncoming traffic.

Absolutely avoid sudden maneuvers like last-minute lane changes or hard braking. Signal early and brake gently. If you must pull over, move completely off the roadway—ideally into a parking lot or rest area. Stopping on the shoulder is extremely hazardous, as other drivers may not see you until it's too late.

Maximize your vehicle's ability to see and be seen. Use your windshield wipers and defroster to keep the glass clear of internal fog and external moisture. In dense fog, slightly lowering your driver's side window allows you to listen for traffic you cannot see, such as approaching trucks at an intersection.

Common Mistake	Why It's Dangerous	Correct Action
Using high beams	Light scatters, creates glare, reduces visibility for you and others.	Use low-beam headlights.
Driving too fast for conditions	Stopping distance exceeds visible distance, leading to rear-end collisions.	Drastically reduce speed.
Tailgating	No time to react if the lead vehicle stops suddenly.	Increase following distance to 5-6 seconds.
Stopping in a travel lane	Creates a stationary, invisible obstacle for oncoming traffic.	Drive to a safe place off the roadway.

Finally, if the fog becomes so dense that you cannot see safely, the only correct action is to exit the roadway completely. Find a secure parking area and wait for conditions to improve. No appointment or schedule is worth the extreme risk of driving in near-zero visibility.

[VioletDella]

As a long-haul trucker, I've seen every kind of fog on the interstate. The biggest error I watch car drivers make is speeding. You might feel safe in your lane, but you can't see a stalled vehicle or debris ahead. My rule is simple: if I can't see my stopping distance, I slow down until I can.

Another tip from the cab: your tail lights are my first clue you're there. Please, use your low beams. Those tiny parking lights or DRLs disappear in thick soup. And never, ever stop on the shoulder unless it's a true emergency. I'd rather you keep moving slowly than become a hidden, fixed object I might not see in time.

[RyderMarie]

I remember my driving instructor drilling this into me: "Fog is a visibility killer, and your habits have to change." The first thing people get wrong is the headlights. You instinctively want to see more, so you flip on the brights. It feels right, but it's completely wrong. It just lights up the fog itself, like shining a flashlight on a wall.

He taught me to focus on creating space and time. Increase your following distance dramatically—if you normally follow at two seconds, make it six. This isn't being overly cautious; it's the basic physics of stopping. You also need to listen. Roll your window down a bit to hear engines or tires on wet pavement, especially at blind intersections. It's an extra sense when your eyes are failing you.

[WyattAnn]

After a close call last winter, I changed my whole approach. I was driving my usual speed in patchy fog, thinking it was fine. Then a car appeared out of nowhere, barely taillights in the gloom. I slammed on my brakes and skidded. It was terrifying.

Now I know: fog means immediately slowing down, no debate. I also religiously use my wipers and defroster on high to keep the windshield crystal clear. That internal film of moisture makes everything worse. My new personal rule? If I feel even a hint of anxiety about the visibility, it's already past time to slow down more and increase my distance from other cars.

[LaErin]

From a meteorological standpoint, fog is a cloud on the ground, composed of tiny water droplets that scatter light. This scattering is precisely why high-beam headlights are counterproductive. The short-wavelength light from high beams diffuses intensely, blinding the driver. Low beams, with their different focus and often a warmer color temperature, penetrate slightly better with less backscatter.

The real danger is underestimating density. Visibility can drop from 1/4 mile to 100 feet in seconds, especially in valley or radiation fog. Your speed must be a function of your actual visual range, not the posted limit. Furthermore, fog often coincides with slick roads from dew or frost, reducing traction. Your stopping distance is therefore doubly compromised—by both sight and grip.

The safest strategy is a holistic adjustment: reduce speed for visibility, increase distance for reaction time, use correct lights for optics, and maintain clear windows for optics. Treat it as a combined environmental challenge, not just a simple matter of "seeing less."