Planning around the lunar cycle

Pick the dates from geometry, then check the weather when it gets close. The dark window moves about fifty minutes later each night, and the usable moonless stretch collapses to nothing around full moon.

The moon rises roughly fifty minutes later each day, so the relationship between moonlight and darkness shifts steadily through the month. Around new moon the entire night is available. Through the waxing half the moon dominates the evening and clears out before dawn. After full it does the reverse, taking the morning.

That means "dark hours" is not a property of the date alone — it depends on which half of the night you can actually be out for. Someone who can only observe before midnight has a completely different good-nights calendar from someone who can stay until dawn.

The moonless night planner draws all of this as a strip, one row per night, with astronomical darkness unshaded and the qualifying window bracketed inside it. Filter it by how much continuous darkness you need and how much moon you will tolerate, and the shape of the coming month is obvious at a glance.

REVIEWED 2026-08-12 · SOURCES: MET Norway, sun and moon positions computed on our own servers