JMA Data MCP

Instructions

Implementation Reference

• jma_data_mcp/server.py:267-299 (handler)

  The handler function for 'get_weather_time_series' tool. Decorated with @mcp.tool() for registration in FastMCP. Validates inputs, fetches data using helper from weather.py, adds station info, and returns the result.
  @mcp.tool() async def get_weather_time_series( station_code: str, hours: int = 24, interval_minutes: int = 60, ) -> dict: """Get time series weather data for a station. Useful for analyzing weather trends over hours or days. Args: station_code: Station code (e.g., '44132' for Tokyo) hours: Number of hours to fetch (default: 24, max: 168 for ~1 week) interval_minutes: Interval between data points in minutes (10, 30, or 60) Returns: Time series weather data """ if interval_minutes not in [10, 30, 60]: return {"error": f"Invalid interval: {interval_minutes}. Must be 10, 30, or 60."} time_series_data = await fetch_time_series_data( station_code, hours=hours, interval_minutes=interval_minutes, ) station_info = get_station(station_code) if station_info: time_series_data["station_info"] = station_info return time_series_data
• jma_data_mcp/weather.py:266-340 (helper)

  Core helper function that implements the time series fetching logic by looping over past time intervals, querying JMA API, parsing data with _parse_station_data, handling errors, and returning structured time series data.
  async def fetch_time_series_data( station_code: str, hours: int = 24, interval_minutes: int = 60 ) -> dict[str, Any]: """ Fetch time series data for a station. Args: station_code: Station code (e.g., '44132' for Tokyo) hours: Number of hours to fetch (default: 24, max recommended: 168 for ~1 week) interval_minutes: Interval between data points in minutes (10, 30, or 60) Returns: Dictionary with time series data """ if interval_minutes not in [10, 30, 60]: interval_minutes = 60 # Limit hours to prevent too many requests hours = min(hours, 168) # Max 1 week start_time = get_latest_data_time() data_points = [] errors = [] # Calculate number of points num_points = (hours * 60) // interval_minutes async with httpx.AsyncClient() as client: for i in range(num_points): target_time = start_time - timedelta(minutes=i * interval_minutes) time_str = format_time_for_api(target_time) url = f'https://www.jma.go.jp/bosai/amedas/data/map/{time_str}.json' try: response = await client.get(url, timeout=10.0) response.raise_for_status() raw_data = response.json() station_data = raw_data.get(station_code) if station_data: parsed = _parse_station_data(station_code, station_data) parsed["observation_time"] = target_time.isoformat() parsed["observation_time_jst"] = target_time.strftime('%Y-%m-%d %H:%M') data_points.append(parsed) except httpx.HTTPStatusError as e: if e.response.status_code == 404: errors.append({ "time": target_time.isoformat(), "error": "Data not available (past retention period)" }) break # Stop if we hit the retention limit else: errors.append({ "time": target_time.isoformat(), "error": str(e) }) except Exception as e: errors.append({ "time": target_time.isoformat(), "error": str(e) }) # Reverse to chronological order data_points.reverse() return { "station_code": station_code, "requested_hours": hours, "interval_minutes": interval_minutes, "data_points": len(data_points), "time_series": data_points, "errors": errors if errors else None }
• jma_data_mcp/weather.py:343-436 (helper)

  Supporting helper that parses raw JSON data from JMA API into structured weather observations for each time point in the series.
  def _parse_station_data(code: str, data: dict[str, Any]) -> dict[str, Any]: """Parse raw station data into structured format.""" station_data: dict[str, Any] = {"code": code} # Temperature (℃) if "temp" in data: station_data["temperature"] = { "value": parse_observation_value(data["temp"]), "unit": "℃" } # Humidity (%) if "humidity" in data: station_data["humidity"] = { "value": parse_observation_value(data["humidity"]), "unit": "%" } # Pressure (hPa) if "pressure" in data: station_data["pressure"] = { "value": parse_observation_value(data["pressure"]), "unit": "hPa" } # Sea level pressure (hPa) if "normalPressure" in data: station_data["sea_level_pressure"] = { "value": parse_observation_value(data["normalPressure"]), "unit": "hPa" } # Wind if "wind" in data: wind_speed = parse_observation_value(data["wind"]) wind_dir_code = parse_observation_value(data.get("windDirection", [None, None])) wind_dir = None wind_dir_ja = None if wind_dir_code is not None: wind_dir_code = int(wind_dir_code) wind_dir = WIND_DIRECTIONS.get(wind_dir_code) wind_dir_ja = WIND_DIRECTIONS_JA.get(wind_dir_code) station_data["wind"] = { "speed": wind_speed, "speed_unit": "m/s", "direction": wind_dir, "direction_ja": wind_dir_ja, "direction_code": wind_dir_code } # Precipitation precipitation = {} if "precipitation10m" in data: precipitation["10min"] = parse_observation_value(data["precipitation10m"]) if "precipitation1h" in data: precipitation["1h"] = parse_observation_value(data["precipitation1h"]) if "precipitation3h" in data: precipitation["3h"] = parse_observation_value(data["precipitation3h"]) if "precipitation24h" in data: precipitation["24h"] = parse_observation_value(data["precipitation24h"]) if precipitation: station_data["precipitation"] = { **precipitation, "unit": "mm" } # Sunshine if "sun1h" in data: station_data["sunshine"] = { "1h": parse_observation_value(data["sun1h"]), "unit": "hours" } # Snow snow = {} if "snow" in data: snow["depth"] = parse_observation_value(data["snow"]) if "snow1h" in data: snow["1h"] = parse_observation_value(data["snow1h"]) if "snow6h" in data: snow["6h"] = parse_observation_value(data["snow6h"]) if "snow12h" in data: snow["12h"] = parse_observation_value(data["snow12h"]) if "snow24h" in data: snow["24h"] = parse_observation_value(data["snow24h"]) if snow: station_data["snow"] = { **snow, "unit": "cm" } return station_data