Moon · September 2026
Moon calendar for Boulder, Colorado, United States: September 2026
Daily moon phases, illumination, moonrise and moonset in Boulder, Colorado, United States for September 2026. Full moon: September 26, 2026. All times are shown in the local time of Boulder, Colorado, United States.
Full moonSaturday, September 26, 2026, 3:33 PM
New moonThursday, September 10, 2026, 6:18 PM
| Day | Phase | Illumination | Moonrise | Moonset |
|---|---|---|---|---|
| 1 | Waning Gibbous | 78% | 9:23 PM | 11:41 AM |
| 2 | Waning Gibbous | 68% | 9:46 PM | 1:06 PM |
| 3 | Last Quarter | 56% | 10:26 PM | 2:20 PM |
| 4 | Last Quarter | 45% | 11:36 PM | 3:37 PM |
| 5 | Waning Crescent | 33% | — | 4:28 PM |
| 6 | Waning Crescent | 22% | 12:32 AM | 5:33 PM |
| 7 | Waning Crescent | 13% | 2:03 AM | 6:09 PM |
| 8 | Waning Crescent | 7% | 3:30 AM | 6:27 PM |
| 9 | Waning Crescent | 2% | 4:28 AM | 7:12 PM |
| 10 | New Moon | 0% | 5:46 AM | 7:33 PM |
| 11 | New Moon | 1% | 6:58 AM | 7:47 PM |
| 12 | Waxing Crescent | 4% | 8:13 AM | 8:17 PM |
| 13 | Waxing Crescent | 8% | 9:23 AM | 8:27 PM |
| 14 | Waxing Crescent | 15% | 10:20 AM | 9:13 PM |
| 15 | Waxing Crescent | 22% | 11:31 AM | 9:37 PM |
| 16 | Waxing Crescent | 31% | 12:22 PM | 10:17 PM |
| 17 | First Quarter | 40% | 1:31 PM | 10:56 PM |
| 18 | First Quarter | 49% | 2:17 PM | 11:46 PM |
| 19 | First Quarter | 59% | 3:04 PM | — |
| 20 | Waxing Gibbous | 68% | 3:40 PM | 12:34 AM |
| 21 | Waxing Gibbous | 76% | 4:19 PM | 1:42 AM |
| 22 | Waxing Gibbous | 84% | 4:32 PM | 2:37 AM |
| 23 | Waxing Gibbous | 90% | 5:21 PM | 3:51 AM |
| 24 | Waxing Gibbous | 96% | 5:37 PM | 4:47 AM |
| 25 | Waxing Gibbous | 99% | 5:53 PM | 5:59 AM |
| 26 | Full Moon | 100% | 6:22 PM | 7:14 AM |
| 27 | Waning Gibbous | 99% | 6:31 PM | 8:17 AM |
| 28 | Waning Gibbous | 95% | 7:21 PM | 9:33 AM |
| 29 | Waning Gibbous | 89% | 7:42 PM | 10:32 AM |
| 30 | Waning Gibbous | 81% | 8:23 PM | 12:00 PM |
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Frequently asked questions
When is the full moon in September 2026 in Boulder, Colorado, United States?
The full moon peaks on Saturday, September 26, 2026, 3:33 PM (local time).
When is the new moon in September 2026?
The new moon falls on Thursday, September 10, 2026, 6:18 PM (local time) — the darkest nights of the month, best for stargazing.
Data: Meeus astronomical algorithms. How we calculate this
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