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 | No moon-free core hours | 0 | 58% |
| February | 15 | February 10 to 16 | 1.2 | 49% |
| March | 37 | March 9 to 15 | 2.6 | 44% |
| April | 60 | April 6 to 12 | 4.0 | 39% |
| May | 58 | May 3 to 9 | 5.3 | 42% |
| June | 42 | June 1 to 7 | 6.6 | 58% |
| July | 42 | July 1 to 7 | 6.3 | 58% |
| August | 42 | August 1 to 7 | 4.2 | 58% |
| September | 24 | September 21 to 27 | 2.5 | 61% |
| October | 12 | October 18 to 24 | 1.1 | 55% |
| November | 0 | No moon-free core hours | 0 | 50% |
| December | 0 | Core not visible | 0 | 54% |
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
- April: April 11 is the best night. The core is above 10 degrees and the moon is down from 1:51 am to 5:51 am, with the moon 31% lit that night.
- May: May 9 is the best night. The core is above 10 degrees and the moon is down from 12:01 am to 5:21 am, with the moon 18% lit that night.
- June: June 4 is the best night. The core is above 10 degrees and the moon is down from 10:21 pm to 5:11 am, with the moon 0% 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 Dry Tortugas National Park
Dry Tortugas is a cluster of small islands about 70 miles west of Key West, Florida. Most of the park is open water, and most of what you see on land is Fort Jefferson, a giant six-sided brick fort. You can get there only by boat or seaplane, so day trips are the norm.
Ponce de Leon named the islands in 1513 after the sea turtles he found there. The fort was started in 1846 and never finished, and it later served as a military prison. It became a national monument in 1935 and a national park in 1992.
Dry Tortugas National Park is a national park in Florida. The National Park Service places its center at 24.63 degrees north and 82.87 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 Dry Tortugas National Park compares
Its best monthly core score of 60 ranks 25 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 Dry Tortugas National Park runs from 39% in April to 61% in September.
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's sky model covers only the contiguous United States and has no value at the reference point used for Dry Tortugas National Park, which is outside its coverage or over water, so no sky darkness figure is shown here.
Questions people ask
When is the best time to see the Milky Way at Dry Tortugas National Park?
April, May and June are the best months. The best week of 2027 is April 6 to 12.
Can you see the Milky Way at Dry Tortugas 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 Dry Tortugas National Park?
The Park Service's sky model covers only the contiguous United States and has no value at the reference point used for Dry Tortugas National Park, which is outside its coverage or over water, so no sky darkness figure is shown here.
Does the moon matter at Dry Tortugas National Park?
Yes. A bright moon hides the Milky Way. The best night in April is April 11, when the moon is 31% lit and the core is above 10 degrees from 1:51 am to 5:51 am.
