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 | 51% |
| February | 8 | February 10 to 16 | 0.7 | 56% |
| March | 23 | March 10 to 16 | 1.9 | 52% |
| April | 40 | April 6 to 12 | 3.1 | 47% |
| May | 49 | May 3 to 9 | 4.2 | 51% |
| June | 47 | June 1 to 7 | 5.5 | 53% |
| July | 46 | July 1 to 7 | 5.3 | 54% |
| August | 38 | August 1 to 7 | 3.5 | 55% |
| September | 22 | September 21 to 27 | 1.8 | 50% |
| October | 8 | October 18 to 24 | 0.6 | 43% |
| November | 0 | Core not visible | 0 | 43% |
| December | 0 | Core not visible | 0 | 52% |
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 6 is the best night. The core is above 10 degrees and the moon is down from 12:42 am to 4:52 am, with the moon 1% lit that night.
- June: June 3 is the best night. The core is above 10 degrees and the moon is down from 10:52 pm to 4:22 am, with the moon 1% lit that night.
- July: July 1 is the best night. The core is above 10 degrees and the moon is down from 10:22 pm to 3:52 am, with the moon 5% lit that night.
Clock times are Eastern time with daylight saving applied. The best nights fall around the new moon, so the dates shift by about 11 days each year.
About Congaree National Park
Congaree is a low, wet forest on the floodplain of the Congaree River in South Carolina. It holds some of the tallest trees in the eastern United States, including loblolly pines. A raised boardwalk keeps your feet dry, and in late spring the fireflies flash in synchrony.
Most of the bottomland forests in the South were cut, but a local campaign that began in 1969, when new logging threatened this one, saved it. It became a national monument in 1976 and a national park in 2003.
Congaree National Park is a national park in South Carolina. The National Park Service places its center at 33.79 degrees north and 80.75 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 Congaree National Park compares
Its best monthly core score of 49 ranks 35 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 Congaree National Park runs from 43% in November to 56% 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 Congaree National Park, it puts the added glow at about 4.8 times the natural brightness of a moonless sky (a ratio of 4.792). That makes it 42nd 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 Congaree National Park?
May, June and July are the best months. The best week of 2027 is May 3 to 9.
Can you see the Milky Way at Congaree 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 Congaree National Park?
The Park Service models how much artificial light brightens the sky across the lower 48. At the point used for Congaree National Park, it puts the added glow at about 4.8 times the natural brightness of a moonless sky (a ratio of 4.792). That makes it 42nd 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 Congaree National Park?
Yes. A bright moon hides the Milky Way. The best night in May is May 6, when the moon is 1% lit and the core is above 10 degrees from 12:42 am to 4:52 am.
