Why one side of the bus gets so much sun
A bus is a glass corridor. When the sun sits on one flank, that row of windows turns into a radiator — glare, UV and heat on one side, relative calm on the other. The pattern is predictable if you know morning vs afternoon and which way you’re travelling.
Morning: sun from the east
After sunrise the sun is low in the eastern sky. Windows facing east catch a long, sharp beam; west-facing seats stay in relative shade. On an eastbound morning ride you often feel the sun through the windscreen too — another reason the front rows can feel harsher than the middle.
Afternoon: sun from the west
By mid-afternoon the sun has swung west. West-facing windows bake; east-facing seats cool down. Late-day light is still strong enough to heat a packed cabin, especially on elevated roads with little building cover.
Midday and the southern sky
In Hong Kong, Taipei and Tokyo the midday sun tracks across the southern sky. South-facing windows take the worst of it; north-facing seats are usually the safer default when you can’t tell east from west at a glance.
Why the “hot side” flips mid-route
Turns, loops and return trips reverse the bus’s heading relative to the sun. The same seat that was cool on the outbound leg can be exposed on the way back. That’s why a fixed rule like “always sit on the left” fails — you need sun position and heading together.
What to do about it
For the quick rule of thumb, readwhich side of the bus is shaded. For a live answer before you board, open 見光死 Shade Chaser: it matches real-time sun azimuth to your route and draws shaded vs exposed seat zones — including Hong Kong building shadows.
Frequently asked questions
Why is one side of the bus hotter than the other?
Because sunlight enters through the windows on the side facing the sun. The opposite side stays cooler until the bus turns or the sun moves.
Is morning sun worse than afternoon sun?
Both can be fierce. Morning sun is low and often in your eyes on eastbound rides; afternoon sun is hotter and hits west-facing windows hard. Midday UV is usually strongest even when the angle is higher.
Does the sunny side stay the same all day?
No. The sun’s azimuth shifts from east to west, and your bus heading changes with every turn — so the sunny side can flip during a single journey.
How do I know which side will bake before I board?
Combine time of day with direction of travel — or open 見光死 Shade Chaser, which reads live sun position against your route heading and shows shaded vs exposed seat zones.
