The core clears 10 degrees during full darkness on most nights from March to September. In January, February, October, 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 | 60% |
| February | 0 | No moon-free core hours | 0 | 64% |
| March | 7 | March 10 to 16 | 0.8 | 64% |
| April | 15 | April 6 to 12 | 1.6 | 63% |
| May | 24 | May 4 to 10 | 2.5 | 62% |
| June | 44 | June 1 to 7 | 3.6 | 52% |
| July | 47 | July 1 to 7 | 3.3 | 44% |
| August | 28 | August 1 to 7 | 2.0 | 44% |
| September | 11 | September 1 to 7 | 0.8 | 43% |
| October | 1 | October 1 to 7 | 0.1 | 53% |
| November | 0 | Core not visible | 0 | 56% |
| December | 0 | Core not visible | 0 | 62% |
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
- June: June 6 is the best night. The core is above 10 degrees and the moon is down from 11:13 pm to 2:53 am, with the moon 9% lit that night.
- July: July 1 is the best night. The core is above 10 degrees and the moon is down from 11:03 pm to 2:23 am, with the moon 5% lit that night.
- August: August 1 is the best night. The core is above 10 degrees and the moon is down from 10:23 pm to 12:23 am, with the moon 0% 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 Wind Cave National Park
Wind Cave in South Dakota has one of the longest caves in the world and a famously odd feature: boxwork, thin calcite fins that look like honeycomb. The cave breathes in and out as air pressure changes, and the wind at the entrance can be strong. Above ground, bison, pronghorn and prairie dogs live on the grasslands.
It was made a national park in 1903 by Theodore Roosevelt, the sixth in the system and the first to protect a cave. The Lakota tell of the cave as the place where their people emerged into this world.
Wind Cave National Park is a national park in South Dakota. The National Park Service places its center at 43.58 degrees north and 103.44 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 Wind Cave National Park compares
Its best monthly core score of 47 ranks 39 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 Wind Cave National Park runs from 43% in September to 64% in February.
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 Wind Cave National Park, it puts the added glow at about 28% of the natural brightness of a moonless sky (a ratio of 0.28). That makes it 23rd 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 Wind Cave National Park?
June, July and August are the best months. The best week of 2027 is July 1 to 7.
Can you see the Milky Way at Wind Cave National Park all year?
The core clears 10 degrees during full darkness on most nights from March to September. In January, February, October, 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 Wind Cave National Park?
The Park Service models how much artificial light brightens the sky across the lower 48. At the point used for Wind Cave National Park, it puts the added glow at about 28% of the natural brightness of a moonless sky (a ratio of 0.28). That makes it 23rd 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 Wind Cave National Park?
Yes. A bright moon hides the Milky Way. The best night in July is July 1, when the moon is 5% lit and the core is above 10 degrees from 11:03 pm to 2:23 am.
