High beams or low beams: when must you dim your headlights?

The number to remember: 150 metres.

Short answer: at night, or when the weather requires it, headlights must be on. You must switch from high beams to low beams as soon as you come within 150 m of a vehicle you are about to meet, when you follow a vehicle within 150 m, and on a road that is sufficiently lit.

What the Code says

Turn on your headlights: drivers must turn on their vehicle’s headlights and lights at night or when weather conditions require it (Code de la sécurité routière, Quebec’s Highway Safety Code, s. 424).
Dim your headlights: drivers must reduce the intensity of their front lighting, at any time, when they come within 150 m of a vehicle they are about to meet, when they follow another vehicle within 150 m, or when the road is sufficiently lit (s. 425).
Keep lights clean: headlights, lights and reflectors must be visible from at least 150 m and free of anything that reduces their effectiveness (s. 237). A police officer may require you to clean them (s. 238).

Situation	Lights to use
Poorly lit or unlit road at night, nobody ahead	High beams allowed
Oncoming vehicle within 150 m	Low beams
You are following a vehicle within 150 m	Low beams
Sufficiently lit street or road	Low beams

Source: s. 425; Guide de la route, ch. 4, “Signaler ses intentions et sa présence”.

Good habits, according to the SAAQ

The SAAQ manual Conduire un véhicule de promenade explains how to avoid dazzling others (ch. 4, “Communiquer sa présence et ses intentions”; ch. 5, “Éviter d’aveugler les autres conducteurs”):

Meeting a vehicle: low beams as soon as its headlights are visible.
Following a vehicle: low beams as soon as your headlights light it up.
Being passed: low beams as soon as the other vehicle draws level with you, back to high beams once it is more than 150 m ahead.
Passing: back to high beams once you are level with the vehicle you are passing.
Dazzled: look toward the right edge of the road and slow down if the lights are too blinding.

Flashing your headlights (switching between high and low beams) can warn a driver who is dazzling you or signal your presence; the Code also allows it to signal a pass, in addition to the turn signals (s. 376).

Daytime running lights, rain and fog

Daytime running lights often come on automatically at low intensity. The manual recommends using low beams even during the day to be more visible, and especially in rain, snow, fog and tunnels (ch. 1, “Les phares”; ch. 5, “La pluie”).
In fog, low beams give better visibility than high beams, which create a bright screen. Driving with only fog lights is not recommended when headlights are required, for example at night (ch. 5, “La brume ou le brouillard”).
Fog lights go at the front, at the same height, never higher than the white headlights (Guide de la route, ch. 2, “Les phares antibrouillards”).

Fines set by the Code

Not turning on headlights at night or when the weather requires it (s. 424): $100 to $200 (s. 509).
Not dimming within 150 m (s. 425): $60 to $100 (s. 507).

Key points for the test

150 m: dim your lights for a vehicle you are meeting or following.
Well-lit road: low beams.
Dazzled: look toward the right side of the road.
Fog: low beams, not high beams.

Test yourself on this topic
Original questions with explanations and sources, “Highway Safety Code” section.
Practise for free

Official sources

Code de la sécurité routière (Highway Safety Code, CQLR c. C-24.2), ss. 237, 238, 376, 424, 425, 507 and 509
SAAQ, Guide de la route (4th ed., 2024, French), ch. 2, “Les phares antibrouillards”; ch. 4, “Signaler ses intentions et sa présence”
SAAQ, Conduire un véhicule de promenade (2022 ed., French), ch. 1, “Les phares”; ch. 4, “Communiquer sa présence et ses intentions”; ch. 5, “Éviter d’aveugler les autres conducteurs”, “La pluie”, “La brume ou le brouillard”

General information page, current as of 2026-10-28. If in doubt, the official text prevails. Rules can change: check saaq.gouv.qc.ca and legisquebec.gouv.qc.ca.