The core clears 10 degrees during full darkness on most nights from February to October. In January, November and December it's out of reach, either too close to the Sun or too low in the dark.
Core score by month
| Month | Core score | Best week | Moon-free core hours a night | Average cloud |
|---|---|---|---|---|
| January | 0 | Core not visible | 0 | 62% |
| February | 4 | February 10 to 16 | 0.4 | 57% |
| March | 19 | March 10 to 16 | 1.6 | 52% |
| April | 31 | April 6 to 12 | 2.6 | 52% |
| May | 47 | May 3 to 9 | 3.6 | 48% |
| June | 61 | June 1 to 7 | 4.9 | 39% |
| July | 48 | July 1 to 7 | 4.7 | 52% |
| August | 37 | August 1 to 7 | 3.0 | 50% |
| September | 21 | September 21 to 27 | 1.3 | 38% |
| October | 6 | October 1 to 7 | 0.4 | 37% |
| November | 0 | Core not visible | 0 | 44% |
| December | 0 | Core not visible | 0 | 60% |
Times are for the best seven nights in each month. Moon-free means the moon is below the horizon. The core counts as visible above 10 degrees in full darkness, when the Sun is more than 18 degrees below the horizon.
The best nights in 2027
- May: May 9 is the best night. The core is above 10 degrees and the moon is down from 12:32 am to 4:12 am, with the moon 19% lit that night.
- June: June 6 is the best night. The core is above 10 degrees and the moon is down from 10:42 pm to 3:42 am, with the moon 9% lit that night.
- July: July 2 is the best night. The core is above 10 degrees and the moon is down from 10:22 pm to 3:12 am, with the moon 1% lit that night.
Clock times are Mountain time with daylight saving applied. The best nights fall around the new moon, so the dates shift by about 11 days each year.
About Great Sand Dunes National Park & Preserve
Great Sand Dunes holds the tallest dunes in North America, up to 750 feet tall, against the backdrop of the Sangre de Cristo Mountains in south-central Colorado. In spring and early summer, Medano Creek flows around the dune field in surges that kids love to splash in. You can hike or sandboard on the sand.
It was set aside as a national monument in 1932 and became a national park and preserve in 2004. The Ute, Apache and other peoples crossed this valley long before,.
Great Sand Dunes National Park & Preserve is a national park and preserve in Colorado. The National Park Service places its center at 37.79 degrees north and 105.59 degrees west, and the sky calculations on this page use that point. Visitor information, fees and alerts are on the park's own page. National Park Service (opens in a new tab).
How Great Sand Dunes National Park & Preserve compares
Its best monthly core score of 61 ranks 24 of 54 national park units that can see the core. The highest is Lassen Volcanic National Park at 86, and the lowest is Voyageurs National Park at 13. Cloud at Great Sand Dunes National Park & Preserve runs from 37% in October to 62% in January.
The score ranks months and parks. It isn't a forecast for any night, and it leaves out local weather, smoke and light from nearby towns. How the core score works.
How dark is the sky?
The Park Service models how much artificial light brightens the sky across the lower 48. At the point used for Great Sand Dunes National Park & Preserve, it puts the added glow at about 12% of the natural brightness of a moonless sky (a ratio of 0.119). That makes it 16th darkest of the 47 parks it covers. Lower is darker. This is a model, not a reading taken at the park, and it describes one point, so the edges of a large park can differ.
Questions people ask
When is the best time to see the Milky Way at Great Sand Dunes National Park & Preserve?
May, June and July are the best months. The best week of 2027 is June 1 to 7.
Can you see the Milky Way at Great Sand Dunes National Park & Preserve all year?
The core clears 10 degrees during full darkness on most nights from February to October. In January, November and December it's out of reach, either too close to the Sun or too low in the dark.
How dark is the sky at Great Sand Dunes National Park & Preserve?
The Park Service models how much artificial light brightens the sky across the lower 48. At the point used for Great Sand Dunes National Park & Preserve, it puts the added glow at about 12% of the natural brightness of a moonless sky (a ratio of 0.119). That makes it 16th darkest of the 47 parks it covers. Lower is darker. This is a model, not a reading taken at the park, and it describes one point, so the edges of a large park can differ.
Does the moon matter at Great Sand Dunes National Park & Preserve?
Yes. A bright moon hides the Milky Way. The best night in June is June 6, when the moon is 9% lit and the core is above 10 degrees from 10:42 pm to 3:42 am.
