Which Side of the Plane, Train or Bus to Sit On to Avoid the Sun
Few things ruin a long journey like three hours of sun beating through the window onto your seat. On a train you can't close the blind because it's shared, on a bus there's no blind at all, and on a plane the window seat you fought for turns into a greenhouse.
The good news: which side gets the sun is predictable. Here's the rule of thumb, why it often isn't enough, and how we built Sunway to answer it properly for any route.
The quick rule of thumb
The sun rises in the east, sets in the west, and around midday sits in the south if you're in the Northern Hemisphere (outside the tropics), or in the north in the Southern Hemisphere.
For the Northern Hemisphere, that gives you:
- Travelling east around midday → the sun is on your right. Sit on the left for shade.
- Travelling west around midday → the sun is on your left. Sit on the right.
- Travelling north in the morning → the sun is on your right (east). In the evening it's on your left (west).
- Travelling south in the morning → the sun is on your left. In the evening it's on your right.
- Travelling north at midday → the sun is behind you. Travelling south → it's ahead of you. Either side is roughly equal.
In the Southern Hemisphere, flip the midday cases: the sun is in the north, so heading east at noon puts it on your left.
Why the rule of thumb fails on real trips
The rule assumes you travel in a straight line at one time of day. Real journeys don't:
- Routes curve. A highway that starts heading north can swing east for an hour, and your "shady side" flips with it.
- Trips span hours. Leave at 10:00 and arrive at 15:00, and the sun moves from east through south to west while you travel.
- Seasons change everything. In summer the sun climbs high and rises well north of east. In winter it stays low, and low sun is exactly the kind that comes straight through side windows.
- Flights follow great circles. A flight from Europe to North America arcs far north, so its heading changes continuously over the trip.
To know which side will actually be sunnier over the whole journey, you have to follow the sun along the route. That's what Sunway does.
How Sunway works it out
Sunway breaks your journey into segments and works out, for each one, where the sun is relative to your direction of travel.
1. It builds your actual route. For car and bus trips, Sunway uses real road routes from Apple Maps and splits them into short segments. Flights follow the great-circle path between the two airports. For trains and ferries, where map routing isn't available, it approximates the path and uses longer, smoother segments.
2. It estimates when you'll be where. From your departure time and typical speeds for each mode of transport, Sunway estimates the time you'll pass each point along the route.
3. It calculates the sun's exact position. For each segment, Sunway computes the sun's direction (azimuth) and height above the horizon (altitude) using the solar position formulas published by NOAA. This runs entirely on your phone, with no server involved.
4. It compares the sun with your heading. If the sun sits to the right of your direction of travel, that segment counts toward the right side, and vice versa. Segments where the sun is below the horizon don't count, and neither do moments where it's almost straight ahead or behind.
5. It weighs what really matters. A segment counts more if you spend longer on it and if the sun is higher and stronger. Weak sun just above the horizon counts for less than strong afternoon sun.
The result is a simple split, such as "72% of the sun on the left", and a clear recommendation: sit on the right. If your trip is mostly at night, Sunway tells you that too, and you can sit wherever you like.
Beyond shade: chasing the light
Sometimes you want the sun: the sunset over the coast, or golden light for photos. Because Sunway shows how much sun each side gets, you can use it either way and pick the sunny side on purpose.
The app also has a Sun tab for days when you're not travelling. It shows the sun's arc for your location, with countdowns to sunrise, sunset, golden hour (when the sun is less than 6° above the horizon) and blue hour (when it's 4–6° below). There are modes for daily use, photography, hiking and mindfulness, plus current weather conditions for your trip.
Try it on your next trip
- Open Sunway and enter your origin and destination.
- Pick your transport: car, bus, train, ferry or plane.
- Set your departure time.
- Sunway shows the sun exposure for each side and recommends the seat.
It takes about ten seconds, and it can save you a very long, very warm afternoon.
Frequently asked questions
Which side should I sit on when travelling east?
Around midday in the Northern Hemisphere, sit on the left when heading east, because the sun is on your right. In the Southern Hemisphere the midday sun is in the north, so heading east at noon puts it on your left.
Which side of the plane will the sun be on in the morning?
In the Northern Hemisphere, if you travel north in the morning the sun is on your right (east), and if you travel south it is on your left. In the evening those sides flip.
Why doesn't the rule of thumb always work?
The rule assumes a straight route at one time of day. Real routes curve, long trips span hours as the sun moves, seasons change the sun's height, and flights follow great-circle paths whose heading changes continuously.
How does Sunway choose the shady seat?
Sunway splits your route into segments, estimates when you'll pass each one, and calculates the sun's position with NOAA's solar formulas on your phone. It weighs each segment by duration and sun strength, then gives a split such as "72% of the sun on the left" and recommends a side.