Sun Glare and Driving: Why the Worst Glare Comes Near the Equinoxes

This planning guide supplements, rather than replaces, official road-safety advice. See the National Highway Traffic Safety Administration’s visibility and glare guidance, and never interact with a phone or calculator while driving.

Every driver knows the moment. You crest a hill or turn onto a straight stretch of road, and the sun sits exactly at the end of it, a white disk balanced on the pavement. The visor is too high to help, the windshield lights up like frosted glass, and for a second or two you are driving on memory.

That moment is not random. It is a predictable product of solar geometry, road layout, and the clock, and it clusters at specific times of year. If your commute runs east in the morning or west in the evening, the worst weeks are the ones around the spring and fall equinoxes, roughly mid-March and mid-to-late September in the United States.

Understanding why lets you plan around it, because unlike weather, the sun’s position is knowable to the minute, days or years in advance.

Why Low-Angle Sun Is So Hard to Drive Into

At midday the sun sits high in the sky. Its light comes down at a steep angle, your car’s roof and the top of the windshield frame block it, and it never lands directly in your eyes while you look at the road.

Near sunrise and sunset the geometry flips. The sun sits within a few degrees of the horizon, which puts it at nearly the same height as your line of sight down the road. Three things happen at once:

1. Direct light enters your eyes. You are looking at the road, and the sun is essentially on the road. Your visual system copes with bright scenes by adapting, but it cannot adapt to the sun’s disk and the shaded pavement beneath it at the same time. Traffic lights, brake lights, and pedestrians in that direction lose contrast.
2. Your windshield scatters the light. Glass is never perfectly clean. A thin film of road grime outside, plus the haze that builds up inside from plastic off-gassing and fingerprints, scatters low-angle light across the entire pane. A windshield that looks fine at noon can turn milky white when the sun hits it edge-on.
3. The road itself becomes a mirror. At shallow angles, asphalt reflects far more light than it does at noon, an effect that gets dramatically worse when the pavement is wet. A rain shower followed by a clearing western sky at sunset is one of the most blinding combinations a driver can face.

None of this is about brightness alone. The midday sun is just as bright. The problem is the angle: low sun puts the light source inside the exact strip of the scene you must watch to drive.

Why the Equinoxes Are Glare Season on East-West Roads

Here is the part most drivers never connect. The sun does not rise in the same spot all year. In the U.S., it rises well north of due east in June and well south of due east in December. Only near the equinoxes, around March 20 and September 22, does the sun rise almost exactly due east and set almost exactly due west. This is true at every latitude, from Miami to Anchorage.

That matters because American roads are overwhelmingly built on east-west and north-south lines. The Public Land Survey System laid a north-south/east-west grid across most of the country west of the original colonies, and city street grids, county roads, and long stretches of interstate follow it. If your commute includes a due-east or due-west segment, then for a week or two around each equinox, the rising or setting sun sits directly down the axis of the road, not off to one side where the visor or the A-pillar can catch it.

The Manhattanhenge effect, everywhere

New York’s famous “Manhattanhenge” is exactly this phenomenon made photogenic: the setting sun aligns with Manhattan’s cross streets and fills them with light from end to end. Because Manhattan’s grid is rotated about 29 degrees from true east-west, its alignment dates fall in late May and mid-July rather than at the equinox. But the underlying effect belongs to any grid city. In Chicago, whose grid runs true east-west, the setting sun lines up with the major east-west streets right around the equinoxes themselves. The same is true in Phoenix, Denver, Houston, and thousands of smaller grid towns.

Photographers chase these alignments. Drivers just get them, twice a year, aimed straight down the commute.

A useful mental model: in summer and winter, a low sun is an off-axis problem you can often block with the visor swung to the side window. Near the equinoxes on a grid road, it is an on-axis problem, dead center in the windshield, at the same height as the car in front of you.

Why Glare Season Lands in Rush Hour

Angle and alignment explain where the glare is. The clock explains why so many people meet it at 7:30 in the morning.

Around the equinoxes, day and night are close to equal, which means sunrise falls near 7 a.m. and sunset near 7 p.m. local clock time in most of the country. Those are commuting hours. In June, by contrast, the sun in most U.S. cities rises before the bulk of the morning commute and sets after most people are home, so even though the sun is low twice every day, fewer drivers are on the road to meet it.

Daylight saving time sharpens both edges:

• March: The spring-forward change lands within days of the equinox. Sunrise jumps about an hour later on the clock overnight, dropping it right back into the heart of the morning commute just as the sun is crossing due east. Drivers who had been commuting in comfortable daylight suddenly spend a week or two driving straight into a rising sun.
• November: The fall-back change pulls sunset roughly an hour earlier on the clock, moving it from after the evening commute to the middle of it. The sun by then sets south of due west, so the perfect down-the-road alignment has passed, but the low evening sun still lands in the windshield for millions of westbound drivers.

If you have noticed that glare seems to ambush you in the weeks right after a clock change, that is not your imagination. The mechanics of how the clock shifts move sunrise and sunset relative to your schedule are covered in detail in how daylight saving time changes sunrise and sunset.

What Actually Helps

You cannot move the sun, but a handful of habits meaningfully cut the risk.

Clean the windshield, inside and out

This is the highest-value item on the list and the most neglected. Scatter, not the direct disk of the sun, is what turns the whole windshield white, and scatter comes from film on the glass. Clean the outside regularly, keep washer fluid topped up, and replace wiper blades that streak. Then clean the inside with a glass cleaner and a microfiber cloth; the interior haze from off-gassing plastics rebuilds over weeks and is invisible until low light hits it. Avoid glossy “protectant” products on the dash top, which reflect up into the glass.

Use the visor early and correctly

Drop the visor before you turn into the sun, not after you are blinded. On east-west commutes near the equinox, the sun will be low enough that the visor at its normal position may not reach it; most visors slide along their mounting rod to extend coverage. When the sun is off-axis, unclip the visor and swing it to the side window.

Wear real sunglasses, ideally polarized

Polarized lenses are built for exactly this situation. Light reflected off horizontal surfaces such as wet asphalt and hoods becomes horizontally polarized, and polarized lenses filter that component specifically, cutting road-mirror glare more than plain tinted lenses of the same darkness. Two caveats: no lens helps against the sun’s direct disk, and polarized lenses can make some LCD dashboard and pump displays look dark at certain angles. Keep the sunglasses in the car, not the house, because the March morning that needs them is the one you did not plan for.

Add following distance and slow down

Glare compresses your effective visibility the same way fog does, except it is worse in one specific direction. Brake lights ahead of you are washed out, pedestrians and cyclists in the bright zone nearly disappear, and every other driver heading your direction is equally impaired. Extra following distance is the cheapest insurance available. Turn on your headlights too. They do nothing for your own vision, but they make you visible to drivers who are squinting into the same sun from the other direction, or watching you in a sun-flooded mirror.

Know the sun’s schedule before you leave

The single most underused tactic is simple foresight. Sunrise and sunset times are exact and published. If you know the sun rises at 7:04 and your eastbound stretch starts at 7:10, you know before you leave the driveway that you are driving into it.

Using a Sun-Times Page to Plan Around Glare

This is where a sunrise/sunset site earns its keep as a driving tool, not just a curiosity. A few minutes with your city’s page turns glare from an ambush into an appointment:

1. Check today’s sunrise and sunset for your city, for example New York or Chicago. The sun is at its most blinding for roughly the first and last 30 to 45 minutes of the day, while it sits within about 10 degrees of the horizon.
2. Compare against your commute window. If your eastbound drive falls inside that post-sunrise window, you are in glare territory. If it starts an hour after sunrise, the sun has climbed high enough that the roofline blocks it.
3. Shift by fifteen minutes when it matters. Near the equinoxes, sunrise moves by only a minute or two per day, but you can move. Leaving 15 to 20 minutes earlier or later can take the sun from dead-ahead to comfortably above the windshield header, or let you complete the eastbound leg before the sun clears the horizon.
4. Reroute the worst segment. If one long due-west arterial is the problem at sunset, a parallel route with a slight north-south zigzag keeps the sun off-axis, where the visor works. Grid cities make this easy: the same layout that creates the alignment also provides parallel escapes.
5. Look ahead on the calendar. Because sunrise direction drifts through the seasons, glare season on any given road is predictable weeks out. Mark the equinox weeks and the two DST change dates, and expect the sharpest conditions then.

The Main Idea

Sun glare feels like bad luck, but it is scheduled. Low sun is a twice-daily event; the equinoxes point it due east and due west, straight down America’s grid of roads; and the clock, especially right after a DST change, places it squarely in rush hour. A clean windshield, polarized lenses, extra following distance, and a glance at your local sunrise and sunset times before you leave will not move the sun, but they will keep it from surprising you, and surprise is most of the danger.