Moon Phases September 2031
The full moon in September 2031 is on 1 September at 09:20 UTC — traditionally called the Harvest Moon. The new moon falls on 16 September at 18:46 UTC. September 2031 holds a second full moon on 30 September at 18:57 UTC — a Blue Moon. Times are UTC.
Why the September 2031 full moon is called the Harvest Moon
The full moon falling nearest the September equinox — it rises unusually soon after sunset for several nights running, which once let farmers work late.
These are the traditional Colonial and Native American names popularised by the farmers’ almanacs. They are folklore, not astronomy — the phase dates and times on this page are computed and verifiable, the names are naming convention.
Moon phase day by day
| Day | Phase | Illumination |
|---|---|---|
| 1 | Full Moon | 100% |
| 2 | Full Moon | 98% |
| 3 | Waning Gibbous | 94% |
| 4 | Waning Gibbous | 87% |
| 5 | Waning Gibbous | 80% |
| 6 | Waning Gibbous | 71% |
| 7 | Last Quarter | 61% |
| 8 | Last Quarter | 51% |
| 9 | Last Quarter | 42% |
| 10 | Last Quarter | 33% |
| 11 | Waning Crescent | 24% |
| 12 | Waning Crescent | 17% |
| 13 | Waning Crescent | 10% |
| 14 | Waning Crescent | 5% |
| 15 | New Moon | 2% |
| 16 | New Moon | 0% |
| 17 | New Moon | 1% |
| 18 | New Moon | 3% |
| 19 | Waxing Crescent | 8% |
| 20 | Waxing Crescent | 15% |
| 21 | Waxing Crescent | 23% |
| 22 | First Quarter | 33% |
| 23 | First Quarter | 44% |
| 24 | First Quarter | 56% |
| 25 | First Quarter | 67% |
| 26 | Waxing Gibbous | 77% |
| 27 | Waxing Gibbous | 86% |
| 28 | Waxing Gibbous | 93% |
| 29 | Full Moon | 98% |
| 30 | Full Moon | 100% |
Illumination at noon (UTC) for each day.
Frequently asked questions
When is the full moon in September 2031?
The full moon in September 2031 is on 1 September at 09:20 UTC, traditionally called the Harvest Moon.
What time is the full moon in September 2031?
The moon reaches full phase at 09:20 UTC on 1 September. It looks full to the naked eye for about a day either side of that instant, so the nights before and after are both worth watching.
Why is the September 2031 full moon called the Harvest Moon?
The full moon falling nearest the September equinox — it rises unusually soon after sunset for several nights running, which once let farmers work late. These names come from Colonial and Native American tradition and were popularised by the farmers' almanacs — they are naming convention rather than astronomy, while the phase dates and times on this page are computed and verifiable.
When is the new moon in September 2031?
The new moon in September 2031 is on 16 September at 18:46 UTC.
Is there a Blue Moon in September 2031?
Yes. September 2031 holds two full moons — the second, on 30 September at 18:57 UTC, is a Blue Moon under the common "second full moon in a calendar month" definition. It is not actually blue.