The conditions are just right to surround Takeda Castle with a sea of clouds.

There’s really never a bad time to visit the ruins of Takeda Castle. A frequent entry on lists of Japan’s best castles, the 353-meter (1,158-foot) altitude of the mountaintop site, located in the city of Asago in Hyogo Prefecture, provides it with breathtaking views of the surrounding terrain.

But perhaps the best time to visit is right now, and ironically the reason is because those views are likely to be obscured.

The meteorological phenomena, called unkai, or “sea of clouds,” in Japanese, occurs most frequently from September to October, particularly in the early morning. At its most dramatic, unkai makes it appear as though the castle is floating in the sky.

▼ Time-lapse photography of the clouds rolling by both above and below.

So why is autumn the best time to witness unkai? Because the season is the sweet spot for the humidity level needed for these cloud formations. Japan’s summer is often too wet and its winter too dry.

In addition, the relatively large swings between daytime highs and overnight lows at this time of year are ideal for producing the mists that make these photos look so otherworldly.

If you’re looking to see the unkai at its optimal conditions, you’ve still got a few weeks left in which to make your travel plans, and detailed information about how to get to the Takeda Castle ruins can be found here, in English, on Asago City’s official website.

Source: Japaaan, Twitter/@Castella_34

Follow Casey on Twitter, where he’s incapable of hearing about a Japanese castle without plotting a trip to it.