Blue Hour Is Longer Than You Think

The best city light is not an hour and does not appear on any watch. How to actually time it.

Blue hour — the window when sky-light and street-light balance — scales with latitude and season. In Singapore it is twenty minutes and gone; in Reykjavík in December it is functionally the whole afternoon. The rule of thumb: the further from the equator and the closer to winter, the longer the balance holds.

The technical tell is simpler than any app: watch the windows. When interior lights read as warm but the sky still holds colour, you are inside the window. When the sky goes to black felt, it is over — after that you are photographing lamps, not a city.

Arrive forty minutes before you think you need to. The five minutes when the streetlights first flicker on, sky still bright — most photographers are still finding parking.