Why daylight shrinks so quickly in autumn

In early October, the daylight part of the day in Amsterdam shrinks by about four minutes each day. It is measurable: on October 2, 2026, sunrise-to-sunset daylight lasts 11 hours, 32 minutes and 27 seconds—just over four minutes less than the previous day.

Picture a wave across the year

Imagine plotting daylight hours through the seasons. The long summer days form a high point; the short winter days form a low point. Near either turning point the curve is fairly flat. Around the March and September equinoxes it is much steeper. At mid-northern latitudes, that is when day length changes most rapidly: it grows in spring and falls in autumn. Early October is still close to that steep stretch, although the daily loss gradually slows toward winter.

Check the pattern where you live

1. Open a sunrise and sunset table for your town.
2. Compare the day length, not just the sunset time, on two consecutive days in September or October.
3. Repeat with two days near the June or December solstice. The day-to-day difference is much smaller there.

For Amsterdam, the table shows roughly four minutes of daylight lost per day in early October 2026. Your exact number depends on latitude and date.

Why “sine wave” is only a shortcut

Earth’s tilted axis makes the Sun’s apparent path shift over the year in a wave-like pattern. Actual sunrise-to-sunset day length also depends on your location, the horizon, the visible size of the Sun and atmospheric refraction. So the measured curve is not a perfect sine wave. The analogy still captures the useful bit: change is slow near its high and low points and fast in between.

Do not judge the pattern by the clock time of sunset alone. Daylight-saving changes and other astronomical effects shift clock times. Use the day-length column instead. And an equinox does not make daylight and darkness exactly equal to the second.