Moon Phase: September 12, 2025

On this day the Moon will be in a Waning Gibbous. During this phase the Moon can be seen in the early morning daylight hours on the western horizon. This is the first phase after the Full Moon occurs. It lasts roughly 7 days with the Moon’s illumination growing smaller each day until the Moon becomes a Last Quarter Moon with an illumination of 50%. The average Moon rise for this phase is between 9pm and Midnight depending on the age of the phase. The moon rises later and later each night setting after sunrise in the morning.

Visit the September 2025 Moon Phases Calendar to see all the daily moon phase for this month.

Waning Gibbous Phase

The Waning Gibbous on September 12 has an illumination of 70%. This is the percentage of the Moon illuminated by the Sun. The illumination is constantly changing and can vary up to 10% a day. On September 12 the Moon is 20.22 days old. This refers to how many days it has been since the last New Moon. It takes 29.53 days for the Moon to orbit the Earth and go through the lunar cycle of all 8 Moon phases.

Phase Details for - September 12