Fog — Missouri Permit Test

Fog on the Missouri permit test — 3 rules, each with the reason behind it and a question on it while it is fresh.

The rules

In fog, keep your headlights on low beam, because you will see less with high beams on.

High beams bounce off the fog and come back at you as a wall of light.

Keep your headlights on low beam. In fog, you will see less if your lights are on high beam.
Missouri Driver Guide, p.64

If fog becomes so thick that you cannot see, pull off the road and stop, leaving your lights and emergency flashers on.

Stopping in the fog is only safe off the road, and only with lights showing where you are.

If the fog becomes so thick you cannot see, pull off the road and stop. Leave your lights and emergency flashers on.
Missouri Driver Guide, p.64

In fog you should reduce your speed and be alert and ready to stop.

Everything in fog arrives later than it should. Speed is the only part of that you control.

It is very dangerous to drive in fog. If you must drive in fog, you should: • Reduce your speed.
Missouri Driver Guide, p.64

On the test

Which headlights should you use in fog?

Low beams. High beams bounce off the fog and come back at you as a wall of light. Missouri Driver Guide, p.64: “Keep your headlights on low beam. In fog, you will see less if your lights are on high beam.”

How this works

Most practice tests hand you a bank of questions and leave the manual somewhere else. This one puts them together.

You read one law and the reason behind it, then answer a question on that law while it is still fresh. Get it right and you move on; get it wrong and you have found the gap while it is cheap to fix, not on the morning of the exam.

Learning one rule at a time, and proving it immediately, is what turns a manual you skimmed into something you actually know — and it makes studying feel like getting somewhere rather than like waiting to find out.

What it costs

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All Missouri permit topics

Where these come from

Every rule here is checked against Missouri Driver Guide, published by the Missouri Department of Revenue, and against the state code itself. Last checked 2026-09-16.