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 | 50% |
| February | 8 | February 10 to 16 | 0.6 | 50% |
| March | 26 | March 10 to 16 | 1.8 | 44% |
| April | 44 | April 6 to 12 | 3.0 | 40% |
| May | 65 | May 3 to 9 | 4.1 | 35% |
| June | 73 | June 1 to 7 | 5.4 | 27% |
| July | 42 | July 1 to 7 | 5.1 | 58% |
| August | 39 | August 1 to 7 | 3.3 | 53% |
| September | 26 | September 21 to 27 | 1.6 | 37% |
| October | 8 | October 1 to 7 | 0.5 | 32% |
| November | 0 | Core not visible | 0 | 39% |
| December | 0 | Core not visible | 0 | 53% |
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 12 is the best night. The core is above 10 degrees and the moon is down from 1:19 am to 4:19 am, with the moon 42% lit that night.
- May: May 7 is the best night. The core is above 10 degrees and the moon is down from 11:39 pm to 3:39 am, with the moon 5% lit that night.
- June: June 4 is the best night. The core is above 10 degrees and the moon is down from 9:49 pm to 3:19 am, with the moon 0% lit that night.
Clock times are Mountain time, which doesn't observe daylight saving. The best nights fall around the new moon, so the dates shift by about 11 days each year.
About Petrified Forest National Park
Petrified Forest in northeastern Arizona holds one of the world's biggest concentrations of petrified wood, logs that turned to stone over 200 million years ago. The northern part of the park spills into the Painted Desert, where hills show bands of pink, lavender and red. Petroglyphs near Puerco Pueblo hint at the people who lived here.
The area was made a national monument in 1906 and a national park in 1962. Old Route 66 once crossed the park, and a rusting car marks where it ran. Taking petrified wood is illegal.
Petrified Forest National Park is a national park in Arizona. The National Park Service places its center at 34.98 degrees north and 109.79 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 Petrified Forest National Park compares
Its best monthly core score of 73 ranks 11 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 Petrified Forest National Park runs from 27% in June to 58% in July.
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 Petrified Forest National Park, it puts the added glow at about 13% of the natural brightness of a moonless sky (a ratio of 0.134). That makes it 17th 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 Petrified Forest National Park?
April, May and June are the best months. The best week of 2027 is June 1 to 7.
Can you see the Milky Way at Petrified Forest 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 Petrified Forest National Park?
The Park Service models how much artificial light brightens the sky across the lower 48. At the point used for Petrified Forest National Park, it puts the added glow at about 13% of the natural brightness of a moonless sky (a ratio of 0.134). That makes it 17th 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 Petrified Forest National Park?
Yes. A bright moon hides the Milky Way. The best night in June is June 4, when the moon is 0% lit and the core is above 10 degrees from 9:49 pm to 3:19 am.
