The “longest night” is the night that comes with the shortest day of the year in the Northern Hemisphere. It happens around the December (winter) solstice, which falls near December 21 most years (it can shift between Dec 20–22).
This is not caused by day-to-day weather. It happens because Earth’s axis is tilted, so sunlight reaches different latitudes at different angles through the year.
When does the longest night happen?
- Northern Hemisphere: around the December solstice (usually close to December 21).
- The exact length of night depends on latitude: the farther north you go, the longer the night.
Example (Istanbul)
On December 21, 2025, Istanbul’s sunrise is about 08:25 and sunset about 17:38, giving roughly 9 h 13 min of daylight.
Why does it happen?
Earth’s axis is tilted. Around the December solstice, the Northern Hemisphere is tilted away from the Sun:
- the Sun stays lower in the sky,
- daylight is shorter,
- night is longer.
Is the longest night also the coldest time?
Not necessarily. The coldest weeks often arrive later (usually January–February) because land and sea store and release heat slowly.
Why isn’t the earliest sunset exactly on the solstice?
In many places, the earliest sunset happens days before the solstice, and the latest sunrise happens days after it. This comes from the combination of Earth’s axial tilt and the way Earth’s orbital speed affects “solar time.”
When is the longest day?
In the Northern Hemisphere, the June (summer) solstice is the longest day, typically around June 21.
Quick FAQ
Is it always December 21?
Usually, but it can shift between Dec 20–22.
Is it the same everywhere?
The solstice date is global, but night length changes by location and latitude.
Does “longest night” mean 24 hours of darkness?
No. That happens only near the polar circles during polar night.