How Our Mt Fuji Visibility Forecast Works | Methodology [ Home ](https://isfujivisible.com) | [ Weather ](https://isfujivisible.com/mt-fuji-weather) | [ Live Cams ](https://isfujivisible.com/mt-fuji-live-cams) | [ Viewspots ](https://isfujivisible.com/viewspots) | [ Sakura ](https://isfujivisible.com/sakura) | [ Koyo ](https://isfujivisible.com/koyo) | [ Plan ](https://isfujivisible.com/plan-your-trip) | [ Visibility by Month ](https://isfujivisible.com/visibility-by-month/2026) | [ Blog ](https://isfujivisible.com/blog) How Our Visibility Forecast Works ================================= This page explains how the Mt. Fuji visibility forecast on isfujivisible.com is produced: what the score means, why we forecast the two sides of the mountain separately, where the data comes from, and how often everything updates. The 1-10 visibility score ------------------------- Every forecast is expressed as a score from 1 to 10. The score estimates how clearly Mt. Fuji can be seen from a given side of the mountain during a given part of the day. It is a measure of expected view quality, not a probability. | Score | Level | What you can expect | |---|---|---| | 8-10 | Visible | Clear, sharp views of the full mountain. Great conditions for photos. | | 6-7 | Partially Visible | The mountain is recognizable but softened by haze or partly covered by clouds. | | 3-5 | Barely Visible | Only faint outlines or brief glimpses, usually through gaps in clouds. | | 0-2 | Not Visible | The mountain is hidden behind clouds, rain, or thick haze. | Why North and South are forecast separately ------------------------------------------- Mt. Fuji sits between two distinct weather zones. The north side covers Kawaguchiko, Yamanakako, and the rest of the Fuji Five Lakes region, anchored on Lake Kawaguchiko at 35.4990, 138.7704. The south side covers Hakone, Lake Ashi, Gotemba, and the Suruga Bay coastline, anchored on Lake Ashi at 35.2133, 139.0104. The two anchor points sit 38.5 km apart on opposite flanks of a 3,776 metre cone, which is enough separation for them to sit in different air masses on the same morning. Clouds frequently pile against one flank while the other side stays clear, and the mountain itself is what splits them: moist air forced up the windward slope condenses there and descends dry on the lee side. A single visibility number for "Mt. Fuji" would therefore mislead roughly half of the people reading it, so each side carries its own independent score and you pick the one matching where you will actually be standing. Why mornings and afternoons are forecast separately --------------------------------------------------- Visibility around Mt. Fuji follows a strong daily cycle. Mornings are usually the clearest window because the air is cool and stable. Through the day, warming slopes push moist air upward and convective clouds and haze build around the summit, so afternoons are often worse even on generally clear days. Fuji City has measured this directly since 1990 by checking the mountain three times every day. In 2025 the whole of Mt. Fuji was visible on 136 days at the 8:00 AM check (37.3 percent of the year), 96 days at noon (26.3 percent), and 91 days at 4:00 PM (24.9 percent), so the odds fall by roughly a third between breakfast and late afternoon ([Fuji City observation record](https://www.city.fuji.shizuoka.jp/documents/7545/fujisan-kiroku2025.pdf)). Each day on this site therefore carries two scores rather than one daily average that would hide that gap. Data sources and model ---------------------- Weather inputs such as cloud cover, humidity, wind, and precipitation come from [Yr.no](https://www.yr.no/), delivered through the [MET Norway Locationforecast 2.0 API](https://api.met.no/weatherapi/locationforecast/2.0/documentation) under the Norwegian Meteorological Institute's [open data licence](https://api.met.no/doc/License). Visibility scores come from a third-party Japanese forecast provider and are combined with those weather inputs and historical viewing patterns around the mountain. Nothing on this page is generated by a language model. Forecasts cover 10 days ahead, at two locations and two periods per day, which is 40 published scores per refresh. Like every weather-driven prediction, they become more reliable as the date approaches, so a score for tomorrow carries far more weight than a score nine days out. Treat anything past roughly day five as guidance for choosing a week, not as a promise about a specific morning. Update schedule --------------- Visibility scores are re-fetched every hour and the weather tables every six hours, both on Japan Standard Time. Whether a given refresh brings new numbers depends on when the upstream provider publishes, so the homepage carries the timestamp of the most recent change rather than a promised update slot. If that stamp looks old, the data behind it genuinely has not moved. Our 36 [live cameras](https://isfujivisible.com/mt-fuji-live-cams) stream continuously, so a forecast is never the last word. If a score looks marginal and you have a long journey ahead, open a camera pointed at the side you are heading for and look at the mountain yourself before you leave. Checking our track record ------------------------- We archive our daily forecast scores and publish them as monthly statistics. Monthly percentages count a day when at least one forecast period reaches 6 or higher, meaning partially visible or better; the clear "Visible" category begins at 8. You can explore any recorded month on the [visibility by month](https://isfujivisible.com/visibility-by-month/2026) page. The archive currently holds 1,660 scores covering 415 days since July 2025. These are the forecasts we published, kept as published, not observations of what the weather actually did. That distinction matters when you read the monthly percentages: they describe how often we expected Fuji to be out, which is not the same claim as how often it was. What makes this forecast different ---------------------------------- - Two viewpoints: separate forecasts for the North (Kawaguchiko) and South (Hakone) sides of the mountain. - Two periods per day: independent morning and afternoon scores for each of the 10 forecast days. - 36 live cameras around the mountain to verify conditions in real time. - A public archive of past visibility scores, published month by month. - Available in 15 languages. - Built and maintained by a real person. Read more in the [about section](https://isfujivisible.com/about).