Japan Weather Forecast (JMA Official Data)

Get clean, normalized 3-day and weekly weather forecasts for all 47 Japanese prefectures, sourced directly from the Japan Meteorological Agency (JMA / 気象庁) — Japan's national weather service and the single most authoritative weather data source in the country.

JMA publishes its forecast data as free open JSON, but the raw feed is undocumented, Japanese-only, and hard to parse: values are spread across parallel arrays, temperatures arrive as strings (sometimes empty), area hierarchies are cryptic numeric codes, and the 3-day and weekly blocks use different structures. This Actor does all of that work for you and returns one tidy JSON item per prefecture.

What you get

For each requested area (prefecture-level JMA forecast office):

• 3-day forecast — weather text, weather (telop) codes, a machine-friendly weatherCategory (sunny / cloudy / rain / snow), wind, wave height, precipitation probability (%), and point temperatures, each attached to its ISO 8601 timestamp.
• Weekly forecast — daily weather codes, precipitation probability, reliability rank, and min/max temperatures with uncertainty ranges, plus climatological normals (tempAverage, precipAverage).
• Text overview (optional) — the human-written forecast discussion issued by JMA forecasters (Japanese).
• Provenance on every item — fetchedAt timestamp, sourceUrls of the exact JMA files used, official reportDatetime, and the attribution string required by JMA's terms.

Input

Field	Type	Default	Description
areaCodes	array	["130000"]	JMA office codes (e.g. 130000 Tokyo, 270000 Osaka, 016000 Sapporo area, 471000 Okinawa). Full list in the offices object of area.json.
allAreas	boolean	false	Fetch every forecast office (~55, covering all 47 prefectures). Overrides areaCodes.
includeOverview	boolean	true	Also fetch the written overview text.
includeWeekly	boolean	true	Include the 7-day forecast block.
maxAreas	integer	47	Safety cap per run (max 60).
requestIntervalSecs	integer	1	Polite delay between requests to the JMA server.

Output example (abbreviated)

{
  "areaCode": "130000",
  "areaName": "東京都",
  "areaNameEn": "Tokyo",
  "publishingOffice": "気象庁",
  "reportDatetime": "2026-08-15T17:00:00+09:00",
  "forecastThreeDay": {
    "timeSeries": [
      [
        {
          "areaName": "東京地方",
          "areaCode": "130010",
          "entries": [
            {
              "time": "2026-08-15T17:00:00+09:00",
              "weather": "くもり　所により　雨",
              "weatherCode": "200",
              "weatherCategory": "cloudy",
              "wind": "東の風",
              "wave": "０．５メートル"
            }
          ]
        }
      ]
    ]
  },
  "forecastWeekly": { "...": "daily codes, pops, reliability, tempMin/tempMax with ranges" },
  "overview": {
    "targetArea": "東京都",
    "text": "千島近海の高気圧が..."
  },
  "sourceUrls": [
    "https://www.jma.go.jp/bosai/forecast/data/forecast/130000.json",
    "https://www.jma.go.jp/bosai/forecast/data/overview_forecast/130000.json"
  ],
  "attribution": "Source: Japan Meteorological Agency website (出典：気象庁ホームページ https://www.jma.go.jp/)",
  "fetchedAt": "2026-08-16T05:00:00+00:00",
  "errors": []
}

One dataset item = one prefecture-level area. Items with partial failures still come back — missing sections are null and the problem is listed in errors, so your pipeline never breaks.

Use cases

• Weather widgets and dashboards for apps serving Japan
• Travel and logistics planning (typhoon season monitoring across prefectures)
• E-commerce demand forecasting (weather-sensitive products)
• Feeding Japanese weather context into LLM agents via the Apify API/MCP
• Research datasets — daily snapshots of official forecasts and their accuracy

Pricing

This Actor uses usage-based pricing: one billable result per area processed. A full-country snapshot (all 47 prefectures) is a single small run — typically well under a minute of compute. Run it daily on a schedule for a continuously updated national forecast dataset at a predictable cost.

Data source, terms, and attribution

• Data: Japan Meteorological Agency, https://www.jma.go.jp/bosai/forecast/
• JMA's website terms of use (https://www.jma.go.jp/jma/kishou/info/coment.html) follow Japan's Public Data License v1.0, which permits copying, modification, and redistribution, including commercial use, with attribution.
• Every output item carries the required attribution string. If you republish this data, keep the attribution ("出典：気象庁ホームページ" / "Source: Japan Meteorological Agency website") and do not present modified data as if issued by the Government of Japan.
• This Actor is not affiliated with or endorsed by JMA. It contains no personal data.

Fair use of the JMA servers

The Actor fetches a small number of static JSON files over a single connection with a minimum 0.5 s delay between requests and a hard cap of 60 areas per run. A full run performs at most ~121 lightweight requests.

Limitations

• Forecast text (weather descriptions, overview) is in Japanese as issued by JMA; weatherCategory and the numeric fields are language-independent.
• JMA updates forecasts a few times per day (typically 05:00, 11:00, 17:00 JST); polling more often than that returns unchanged data.
• Amber/warning-level information (advisories, typhoon tracks) is out of scope for this Actor.

Important: scope of this Actor

This Actor relays the Japan Meteorological Agency's own published forecasts. It does not generate original predictions, probabilities, indices, or warnings of any kind. Values and wording are passed through unmodified, with the JMA attribution attached to every record.

Under Japan's Meteorological Service Act (Articles 17 and 23), producing original forecasts or issuing warnings requires a licence from the JMA. This Actor is designed to stay outside that scope by never adding interpretation of its own. If you build on top of this data, that responsibility becomes yours.