Why this site exists
The Tokyo Microclimate Observatory started with a commute. Kenji Mori spent eight years riding from Hachioji to Otemachi, and the daily transition — stepping off a cool foothill morning into a ward heat bubble, then reversing it at night — became impossible to un-notice. The weather forecast said one temperature. His body measured two. After fourteen years as a meteorological observer at the JMA Tokyo Regional Headquarters, he knew which one was lying, and it wasn't his body. This site is what happens when a professional observer decides the gap between the forecast and the platform deserves its own record.
We're not a government agency and we don't pretend to be one. We're an independent observation project operated by Oregon Timber Dwellings LLC, publishing zone-level analysis of the Greater Tokyo atmosphere: the 23-ward heat island, the bay's daily moderation, the Tama foothill cooling, the Saitama continental swing, and the Boso Peninsula's oceanic phase shift. Everything we publish traces to a named instrument and a stated method, and everything we get wrong gets a dated entry on the corrections page.
The team
Kenji Mori
Kenji spent fourteen years as a meteorological observer at the JMA Tokyo Regional Headquarters, specializing in urban climatology and heat island monitoring. He led our 2019–2022 mobile survey program — the aspirated-thermometer transects across all 23 wards that produced this site's ward-by-ward bias figures. He grew up in Hachioji, commuted to Otemachi for eight years, and will tell you plainly that he once survived an August on three hours of sleep a night before moving back west. The Tama Hills page is not an abstract analysis for him. It's the reason he can sleep.
Yuki Tanaka
Yuki holds a Tokyo University MSc in urban planning and builds the observatory's analytical layer. She drew the microclimate zone map from AMeDAS ten-minute data and Landsat thermal imagery — the zone boundaries on our map are her discontinuity analysis, not artistic license. She also runs the annual cherry blossom prediction by zone, the closest thing we have to a public performance review: every spring, the stagger between the wards, the hills, and the peninsula either matches her forecast or goes on the corrections page. So far the corrections page is winning less often than she is.
David Park
David works as a Kanto agricultural extension advisor and has tracked frost damage and baiu behavior for Saitama rice cooperatives for over a decade. He mapped the Saitama dry slot from forty cooperative rain gauges — the densest private gauge network in the northern plain — and his frost-pocket records are why our January zone figures carry garden-scale confidence. When a kura storehouse in Kawagoe holds 19°C through an August afternoon, David has the logger data to prove it.
What we believe about measurement
Three commitments run the project. First: measured or nothing. When a live feed drops, our boxes say “Updating…” — we never paste in plausible numbers. Second: provenance before precision. Every figure carries its instrument and its baseline period, and when our number differs from the official one, both numbers get printed with the reason for the difference. Third: the corrections ledger is a feature. A site about observation that hides its errors is selling something. We're not selling certainty; we're selling an honest instrument record of the air over the Kanto plain.
How the project is funded
The observatory is operated by Oregon Timber Dwellings LLC, a Washington State company, with a Japan office in Shibuya. We publish the zone analysis free, and we sell detailed climate guides — the long-form residential and travel briefings described on the refund policy page — to readers who want the full depth. There is no advertising on this site, no sponsored content, and no affiliate links. The guides are the whole business model, which keeps the analysis answerable to readers rather than to advertisers. The legal and operational details are on the business information page.
A note on the commute
Kenji still rides the Chuo Line with a thermometer. Old habit. The transect vehicle does the rigorous work now — calibrated, aspirated, GPS-logged — but there's a reading he takes at the Shinjuku platform edge every August evening that isn't in any dataset, and he'd rather you didn't ask him to stop taking it. Observation isn't just the method here. It's the personality.
The working method, day to day
A typical observation month has a rhythm. The first week is transect week when weather permits: the vehicle runs its fixed routes across the wards, the Tama cities, the Saitama plain, and the Boso coast, logging at ten-second intervals through pre-dawn, midday, and evening windows. The second week is data week: transect logs are cleaned, the month's AMeDAS and JMA records are pulled, and any divergence between the stationary network and the mobile record gets investigated rather than averaged away. The third week is writing: essays are updated, the corrections queue is processed, and the seasonal matrix is re-checked against the running year. The fourth week is fieldwork of the less instrumented kind — walking the kura district with a handheld logger, sitting out a sea-breeze onset on the Yokohama waterfront, checking the cooperative gauges after a storm. It is not a glamorous process. It is, however, a process, and the site's credibility rests on the difference.
Why five zones and not seven, or three
Readers sometimes ask why the scheme stops at five. Because five is where the discontinuities are. We tested finer splits — separating the northern wards from the southern wards, splitting the bay coast at the Tama mouth — and the added zones didn't hold up as independent thermal regimes across seasons; their signals were weather, not climate. We tested coarser ones too, and the three-zone version erased the dry slot and the delayed spring, which are the two most useful facts a resident can learn from this site. Five is the count that survives the data. When a sixth regime ever demonstrates itself in the record, we'll draw it. The map serves the measurements, not the reverse.
The people behind the numbers, continued
Beyond the three names above, the observatory runs on a small network of cooperators who deserve mention: the forty Saitama farming households who host rain gauges and phone in frost damage; the yacht club at the Yokohama waterfront that logs sea-breeze onset times for us out of sheer meteorological enthusiasm; and a retired JMA instrument engineer who checks our aspirated shields twice a year and accepts payment only in coffee. Zone climatology at this resolution is not something three people can do alone, and this paragraph is our standing acknowledgment that they don't.
What we'd like this site to be
The ambition is modest and specific: to be the reference people check before they sign a lease in a ward they've never slept in, before they book a late-March trip expecting peninsula blossoms, before they tell an elderly parent that the Tachikawa apartment is fine in August. Tokyo's five climates are measured, mapped, and maintained here, one thermometer at a time. If the site keeps its instruments honest and its corrections page current, everything else — the readership, the guides, the occasional gratifying email from someone who chose Hachioji and sleeps well now — takes care of itself.
Our reading recommendations
For readers new to the site's framework, we suggest an order. Start with the front page's zone map to get the five regimes spatially. Read the heat island essay next, because the core's bias is the reference every other zone is measured against. Then the seasonal matrix, which converts the zone essays into a calendar. After that, read the zone you're actually deciding about — the essays are written to stand alone for exactly this reason. Finish with the data sources page, which is the site's warranty document: it tells you what every number is made of, and it's the page we'd want to read if the roles were reversed.
Corrections as culture
One more thing about how the team works, because it explains the site's texture: we keep the corrections page prominent on purpose. Most publications treat corrections as an embarrassment to be minimized. An observation project can't afford that posture — the instrument record is only worth keeping if its errors are kept too, dated and visible. Kenji's habit from the JMA years is the rule here: when two readings disagree, you don't average them and move on; you find out which instrument lied and you write it down. The essays, the matrix, and the map are all products of that rule. So is the corrections page, which we notice is one of the least-read pages on the site and one we consult more than any other.
The observatory's instruments, personally
A word about the tools, because the team is attached to them. The transect vehicle's thermometer package — aspirated, shielded, logging at ten-second intervals — was built to JMA exposure standards and is checked against a reference sensor before every season. The forty Saitama gauges are humble tipping buckets, but each one is reconciled monthly against the Urawa observatory, and David can tell you which two of them sit under trees that grew too ambitious. The cherry blossom predictions run on accumulated temperature models Yuki recalibrates every spring against the previous year's error. None of this is exotic equipment. Urban climatology at useful resolution is mostly discipline wearing inexpensive instruments, and the team's pride lives in the discipline.