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 | 52% |
| February | 3 | February 10 to 16 | 0.2 | 55% |
| March | 17 | March 10 to 16 | 1.4 | 53% |
| April | 31 | April 6 to 12 | 2.4 | 49% |
| May | 47 | May 3 to 9 | 3.4 | 45% |
| June | 71 | June 1 to 7 | 4.6 | 29% |
| July | 60 | July 1 to 7 | 4.5 | 40% |
| August | 48 | August 1 to 7 | 2.8 | 32% |
| September | 22 | September 1 to 7 | 1.2 | 26% |
| October | 5 | October 1 to 7 | 0.3 | 35% |
| November | 0 | Core not visible | 0 | 43% |
| December | 0 | Core not visible | 0 | 55% |
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 5 is the best night. The core is above 10 degrees and the moon is down from 10:27 pm to 3:07 am, with the moon 3% lit that night.
- July: July 1 is the best night. The core is above 10 degrees and the moon is down from 10:07 pm to 2:37 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 9:37 pm to 12:37 am, with the moon 0% lit that night.
Clock times are Pacific 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 Basin National Park
Great Basin is a quiet park in eastern Nevada, far from any big city. Wheeler Peak rises to 13,063 feet, and the bristlecone pines on its flank are among the oldest living things on earth. Lehman Caves, near the visitor center, is a small, richly decorated limestone cave.
Lehman Caves became a national monument in 1922, and the park around Wheeler Peak followed in 1986. In 2016 it was named an International Dark Sky Park, and the park holds regular astronomy programs.
Great Basin National Park is a national park in Nevada. The National Park Service places its center at 38.95 degrees north and 114.26 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 Basin National Park compares
Its best monthly core score of 71 ranks 13 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 Basin National Park runs from 26% in September to 55% in December.
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 Basin National Park, it puts the added glow at about 2% of the natural brightness of a moonless sky (a ratio of 0.02). That makes it 3rd 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 Basin National Park?
June, July and August are the best months. The best week of 2027 is June 1 to 7.
Can you see the Milky Way at Great Basin National Park 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 Basin National Park?
The Park Service models how much artificial light brightens the sky across the lower 48. At the point used for Great Basin National Park, it puts the added glow at about 2% of the natural brightness of a moonless sky (a ratio of 0.02). That makes it 3rd 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 Basin National Park?
Yes. A bright moon hides the Milky Way. The best night in June is June 5, when the moon is 3% lit and the core is above 10 degrees from 10:27 pm to 3:07 am.
