JP Weather Sky started with a simple observation: in a city of 14 million people, almost nobody looks up. They look at phones, at sidewalks, at train schedules, at the backs of other people's heads. But the sky is still there. It is above every rooftop, every expressway, every convenience store. And it is changing, all the time, in ways that are beautiful and meaningful and worth paying attention to. We decided to pay attention. And we decided to tell other people what we saw.

The project began in April 2022, when Hana Suzuki bought a second-hand Olympus OM-D and started photographing the sky from five fixed locations around Tokyo. She chose Odaiba, Mt. Takao, Yoyogi Park, Toyosu, and Shinjuku Southern Terrace because they represented five different relationships with the sky — open water, high elevation, green canopy, eastern waterfront, and urban canyon. She has not missed a day since. That is over three years of daily sky photographs, 5,475 images at last count, documenting cloud types, light conditions, and atmospheric phenomena from the same five perspectives.

David Park joined in September 2022. He is an amateur astronomer who had been frustrated for years by the lack of detailed light pollution data for Tokyo. He bought a Sky Quality Meter, attached it to his bicycle, and rode every street in all 23 wards over six months, taking readings at 2 AM on clear nights. He rode 400 kilometers and took 1,100 measurements. The resulting map is the most detailed light pollution survey of Tokyo ever published. It shows Bortle 9 in the major hubs, dropping to Bortle 8 at the waterfront, Bortle 7 in the western suburbs, and Bortle 5 on Mt. Takao. It is not just data. It is a guide to where you can still see stars.

Yuki Mori came on board in March 2023. She is a meteorology student at the University of Tokyo, specializing in boundary layer dynamics and urban microclimates. She writes the cloud identification guides that help readers name what they are seeing. She fact-checks our observations against JMA data and satellite imagery. She is the reason we do not claim to be meteorologists — she is the meteorologist, and the rest of us are just watching and writing down what we see.

Hana Suzuki — Founder, Cloud Photographer

Hana grew up in Kagoshima, at the southern tip of Kyushu, where the sky is wide and the Sakurajima volcano produces its own weather. She moved to Tokyo for university and spent her first five years in the city without once looking at the sky on purpose. It was just background. Then, in March 2022, she saw a Brocken spectre from the summit of Mt. Takao — her own shadow, huge and dark, surrounded by a rainbow halo, projected on the fog below. She did not know what it was. She thought she was hallucinating. She took a photograph, looked it up when she got home, and spent the next three days reading about atmospheric optics. That is when she started the project.

Her photography is documentary, not artistic. She uses the same camera settings every day, the same five locations, the same framing. The point is consistency, not beauty — though the results are often beautiful anyway. She has documented 14 distinct cloud types over Tokyo, 3 Brocken spectres from Mt. Takao, 4 double rainbows from Odaiba, 2 fog events that created complete whiteouts at street level, and 1 noctilucent cloud sighting that she still cannot fully explain. She has failed to photograph the green flash 12 times. She will try again.

Hana manages the day-to-day operations of JP Weather Sky, coordinates the field observations, and writes the narrative content for the site. She lives in Koto-ku, Tokyo, two kilometers from the Toyosu waterfront. She wakes at 5 AM every day to check the sky and file her observation report. On clear mornings she rides her bicycle to Odaiba before work. On cloudy mornings she sits on her balcony with coffee and waits to see what the clouds do. She has not owned a television in four years. She says the sky is better entertainment.

David Park — Co-founder, Astronomer

David was born in Boulder, Colorado, and grew up under dark Rocky Mountain skies. He moved to Tokyo in 2019 for a job in software engineering and spent his first two years in the city trying to find places to stargaze. He failed. The light pollution was worse than he expected, and the available maps were too coarse to be useful. So he made his own. The 400-kilometer bicycle survey took six months and required him to wake at 1 AM, ride until 4 AM, and still be functional at work the next day. He did it three times a week from October 2022 to March 2023. He lost 8 kilograms and gained a comprehensive dataset.

David's contribution to JP Weather Sky is the quantitative backbone. He built the data infrastructure, the API integrations, and the automated sky quality reports. He maintains the relationship with Open-Meteo, which provides the free forecast data we use for current conditions. He wrote the sunset azimuth calculator that predicts the Manhattanhenge-style alignments for Tokyo's street grid. He is currently developing a machine learning model that predicts fog formation in the Tama River valley based on temperature, humidity, and wind speed data. It is not working yet. He says it will work by winter.

David lives in Nakano, Tokyo, and keeps a Celestron 8-inch telescope on his balcony, which he uses for lunar and planetary observation despite the light pollution. He can see Jupiter's Great Red Spot from Bortle 9 Nakano, which tells you something about his patience and his optics. He visits the Tama River banks every new moon for darker-sky sessions. He has seen the summer Milky Way from Mt. Takao three times. He describes the experience as "like remembering something I had forgotten I knew."

Yuki Mori — Contributor, Meteorology

Yuki is in her final year of a master's degree in atmospheric science at the University of Tokyo. Her thesis research focuses on urban heat island effects on boundary layer cloud formation — specifically, how Tokyo's 4-degree temperature anomaly influences cumulus development over the metropolitan area. She found JP Weather Sky through a Twitter post about the heat island cumulus effect and contacted Hana to offer her expertise. She has been contributing since.

Yuki writes the cloud identification guides and the weather science explainers. She is the reason we know that cumulus congestus over Tokyo reaches an average maximum height of 7,800 meters in August, that the stratocumulus base during tsuyu averages 850 meters with a standard deviation of 200 meters, and that the sea breeze front moves inland at an average speed of 12 kilometers per hour on July afternoons. She gets these numbers from JMA radiosonde data and satellite retrievals, not from guesswork. She keeps us honest.

When she is not studying or writing for JP Weather Sky, Yuki competes in orienteering and teaches introductory meteorology to high school students through a University of Tokyo outreach program. She lives in Komaba, near the university campus, and does most of her sky watching from the roof of the atmospheric science building, which has an unobstructed 360-degree view from 30 meters elevation. It is not Mt. Takao. But it is enough for cloud identification. And the coffee in the department lounge is free.

What We Believe

We believe the sky is not background. It is the main event. It is the largest visible surface on Earth, the only part of the natural world that remains accessible to everyone in a city of this density. You do not need a ticket. You do not need equipment. You just need to look up at the right angle, from the right place, at the right time. We are here to help you find those angles, places, and times.

We believe in honest observation. We do not fake data. When the API is down, we say "Updating..." We do not claim to be certified by any meteorological agency. We are observers, not forecasters. We describe what we see, what the instruments measure, and what the science says about both. If we are wrong, we correct it. Our fix log is public.

We believe Tokyo is worth watching. It is easy to think of this city as nothing but concrete and neon, a place where nature has been subdued. But the sky disagrees. The sky above Tokyo is as complex and beautiful as the sky above any ocean or mountain range. You just have to know where to look. We are looking. Come look with us.

Contact us:
sky@jpweathersky.com
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