How do I cope with low sun glare while driving?

Why a dirty windscreen is the real problem rather than the sun, what to do in the moment you are blinded, and the seasonal preparation that makes the whole autumn easier.

Difficulty: beginner
Time: 12 min
Read: 5 min
Safety: warning

Short answer

Most low-sun dazzle is caused not by the sun but by what it lights up: a film of grease, smears and traffic film on the inside and outside of the windscreen scatters the light into an opaque white sheet. Clean both sides of the glass properly, replace tired wiper blades, keep the washer bottle full of proper screenwash, and keep good sunglasses and the sun visor to hand. In the moment, slow down, increase your gap, and use the kerb line as your reference.

There is a specific and very British version of this problem. In autumn and spring the sun sits low at the times people commute, the roads are wet from overnight damp, and passing traffic throws up a fine oily film that dries onto the screen. Point that screen at a low sun and the film scatters every ray, turning a merely bright morning into a wall of white. The sun itself has not changed; the glass has. That is genuinely good news, because the glass is the one thing in this situation you fully control.

Safety

Low sun is a recorded contributory factor in thousands of UK collisions each year and is at its worst in the hours around sunrise and sunset in autumn and spring, exactly when traffic is heaviest. If you genuinely cannot see, you must not continue — slow down, and stop somewhere safe until the sun moves or the road turns. Being dazzled is not an excuse in law; failing to stop when you cannot see is careless driving.

Step by step

Clean the inside of the windscreen properly.This is the step almost nobody does and the one that makes the biggest difference. The inside accumulates a film from plastics outgassing, breath, and anything smoked or vaped in the car. Use a proper glass cleaner and a microfibre cloth, then a second dry cloth, working across then up and down so you can see which side any remaining smear is on.
Clean the outside and deal with the traffic film.Washing the car is not enough — glass holds a greasy film that a shampoo will not shift. A dedicated glass cleaner or a mild abrasive glass polish removes it. A screen that beads water rather than smearing it is one that will not blind you at sunrise.
Replace the wiper blades before autumn.Blades harden over the summer and then smear all winter. A smearing wiper across a low sun is close to total blindness for a full second, at whatever speed you are doing. New blades every year or so is one of the cheapest safety measures on a car.
Fill the washer bottle with proper screenwash.You will need it constantly through autumn, and plain water neither shifts the greasy film nor resists freezing. Mixed to the strength on the bottle for the coldest weather you expect.
Keep good sunglasses in the car, not in the house.Polarised lenses cut glare from wet road surfaces particularly well. Keep them in the car permanently, because the mornings when you need them are exactly the mornings you were in a hurry. Do not use them at dusk or at night.
Use the visor early rather than after being dazzled.Drop it before you come over the crest, not after. Many visors also slide sideways to block sun coming through the side window, which most drivers never discover.
In the moment, slow down and widen your gap.If you are dazzled, ease off smoothly — do not brake hard, because the driver behind is dazzled too. Increase the gap in front, use the nearside kerb or verge as your steering reference, and be ready for the vehicle ahead to brake without you seeing its lights.
Use dipped headlights so others can see you.A vehicle coming out of a low sun is close to invisible to anyone looking towards it. Dipped headlights make your position readable long before your shape is. This matters most at junctions.
Plan around it if you can.For a few weeks in autumn and spring the sun sits directly along particular roads at particular times. If your commute runs east in the morning and west in the evening, a small change of route or of departure time removes the problem entirely.

Common mistakes

Wiping the inside of the screen with a hand or a sleeve — It spreads the grease into an even film, which is worse than the streaks were. A proper glass cleaner and two cloths take five minutes and last for weeks.
Carrying on because it is only for a minute — At 60 mph, a minute of not being able to see is a mile of road. If you cannot see, you must slow down or stop, and low sun is a recorded factor in a large number of collisions every year.

If it doesn't work

Screen looks clean but goes white in the sun

Cause: A film on the inside of the glass — Fix: Clean the inside. It is the single most common cause and the most consistently neglected — the difference is often startling.

Dazzled at a junction and cannot see approaching traffic

Cause: The sun is directly behind the traffic you need to see — Fix: Wait. Creep only when you are certain, and remember that a car coming out of the sun is invisible to you and you may be invisible to it. This is the specific situation in which low-sun collisions happen.

Traffic lights impossible to read

Cause: Low sun directly behind the signal head — Fix: Slow right down and be prepared to stop. Modern LED signals are worse for this than the old filament ones in some conditions. Take your cue from the traffic around you and from the pedestrian signals if you can see them.

Windscreen chips scatter light badly

Cause: A chip or crack acts as a prism — Fix: Have chips repaired promptly. The catalogue's guide covers when a repair is possible; a chip in the driver's line of sight is also an MOT failure.

Sunglasses make the instruments unreadable

Cause: Very dark lenses in a bright ambient — Fix: Choose a moderate tint rather than the darkest available, and never wear sunglasses into dusk. Going from bright sun into a tunnel or under trees with dark lenses is genuinely dangerous.

Worse after a windscreen replacement

Cause: Residue from the fitting, or a different glass coating — Fix: Clean it thoroughly inside and out. If a distortion or a wave is visible in the glass, raise it with the fitter — that is a defect rather than dirt.

Questions people ask

Why is autumn worse than summer for this?

Two things combine. The sun is lower at the times people actually drive, so it sits at windscreen height rather than overhead. And damp roads, fallen leaves and heavier traffic put more film on the glass. The same sun in July is above the visor and the screen is cleaner.

Do polarised sunglasses help?

Yes, particularly against glare reflected off a wet road surface, which is a large part of the problem. They can make some LCD instrument displays and phone screens look odd or dark, which is worth knowing before you buy an expensive pair.

Is being dazzled by the sun a defence if I have a collision?

No. The obligation is to drive at a speed and in a manner appropriate to the conditions, and that includes slowing or stopping when you cannot see. Being unable to see is a reason to stop, not an excuse for what happens if you do not.