Working out your year…
- Night
- Daylight
- Dazzle, sun within 25°
- Glare, within 15°
- Blinding, within 8°
- Your drive, in it
Drag across the plate, or focus it and use the arrow keys.
Your glare seasons
Is the maths right?
The same engine that draws your plate is checked, live in this page, against two published answers.
Manhattanhenge 2026
The American Museum of Natural History publishes the evenings when the setting sun lines up with Manhattan’s cross streets (bearing 299.1°). On each of their dates, here is the minute Low Sun puts the sun on that bearing.
| AMNH says | Low Sun computes |
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NREL’s reference case
NREL’s Solar Position Algorithm paper (Reda & Andreas, 2004) gives a worked example: Golden, Colorado, 17 October 2003, 12:30:30 local time.
| NREL SPA | Low Sun |
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How it works
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Where the sun is, every minute
For your place, Low Sun computes the sun’s direction and height for every minute you drive, all year, using NOAA’s solar position algorithm, with daylight saving applied from your time zone. It all runs in your browser; nothing about where you drive leaves your device.
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Is it in your eyes?
A low sun counts as glare when it is above the horizon and within 25° of the way you’re facing, across and up: the zone used in road-safety studies of sun glare. Inside that zone the closer it sits to straight ahead, the worse it gets. Veiling glare rises roughly with the inverse square of the angle, so within 15° is about three times worse, and within 8° about ten times worse, than at the 25° edge.
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Dates, not warnings
The glare days group into seasons, usually a few weeks in spring and in autumn for each direction. For each season Low Sun finds the smallest change of departure time that clears every drive in it, and exports each glare drive to your calendar with a reminder an hour before.
What it can’t see
- Weather. It assumes a clear sky. A cloudy glare day is just a day.
- Buildings, trees and hills. They can hide a low sun. They can’t make one appear, so a listed date can only turn out milder, never worse.
- Curves. Each drive is one straight heading. A road that bends spends only part of the drive facing the sun.
- Your car. Visor size, seat height and a dirty windshield change how bad glare feels; the geometry stays the same.
- It’s a planning tool. Use it the night before, never at the wheel. Nothing here guarantees a safe drive.
Already out there
Glare prediction isn’t new, and the rules of this event ask for prior work to be named.
- SunGlare (iOS app): predicts when and where sun glare happens on the roads you drive.
- ZILL: Sun Smart Route Planner (Android app): the sun’s position relative to the road along a trip, with glare alerts.
Low Sun’s difference: it shows a whole year of one commute at once, so the glare seasons are visible months ahead; it gives the smallest change of departure time that avoids each season; it hands those dates to the calendar you already use; it runs entirely on your device with no account; and its maths is checked in public, on this page.