Moon ExactlyDaily lunar detail
September 2031 Moon Calendar
The month opens with a Full Moon and closes with a Full Moon. It contains 5 exact major phase events.
Icons use the common Northern Hemisphere convention: waxing light on the right, waning light on the left. Your sky may appear rotated at other latitudes.
The lunar story of September 2031
New Moon occurs September 16, 2031. Full Moon occurs September 1, 2031. The first major event is Full Moon on September 1, 2031, and the month progresses from 100% to 100% illumination at noon UTC on its boundary dates.
Choosing a day
Select any Moon to open its precise phase angle, illuminated fraction, elapsed age since New Moon, trend, and neighboring event. Date result pages remain shareable but are excluded from search indexing.
Questions, answered
Frequently asked questions
What time are daily phases calculated?
12:00 UTC, chosen deliberately to keep date-only selections stable worldwide.
Why can a local phase event fall on another date?
An event near 00:00 UTC may occur on the previous local date west of Greenwich or the next local date east of it.
Do the icons show sky orientation?
They use a Northern Hemisphere convention; actual orientation rotates with latitude and viewing angle.