{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$id": "https://raw.githubusercontent.com/api-evangelist/wunderground/main/json-schema/observation.json",
  "title": "PWS Observation",
  "description": "A single weather observation record from a Personal Weather Station in the Weather Underground network.",
  "type": "object",
  "properties": {
    "stationID": {
      "type": "string",
      "description": "Unique identifier of the PWS station assigned by Weather Underground.",
      "examples": ["KCASARAT1", "KGASEATT42"]
    },
    "obsTimeUtc": {
      "type": "string",
      "format": "date-time",
      "description": "Observation timestamp in UTC (ISO 8601).",
      "examples": ["2024-01-15T18:32:00Z"]
    },
    "obsTimeLocal": {
      "type": "string",
      "description": "Observation timestamp in the station's local time zone.",
      "examples": ["2024-01-15 10:32:00"]
    },
    "neighborhood": {
      "type": ["string", "null"],
      "description": "Neighborhood or location name provided by the station owner.",
      "examples": ["Downtown", "Hillside Gardens"]
    },
    "softwareType": {
      "type": ["string", "null"],
      "description": "Software or device used to upload observations to the network.",
      "examples": ["WeatherBridge", "WeeWX", "Ecowitt"]
    },
    "country": {
      "type": "string",
      "description": "ISO 3166-1 alpha-2 country code of the station.",
      "examples": ["US", "GB", "DE"]
    },
    "solarRadiation": {
      "type": ["number", "null"],
      "description": "Solar radiation intensity in watts per square meter (W/m²).",
      "minimum": 0,
      "examples": [320.5, 0.0]
    },
    "lon": {
      "type": "number",
      "format": "double",
      "description": "Station longitude in decimal degrees (WGS84).",
      "minimum": -180,
      "maximum": 180,
      "examples": [-122.419]
    },
    "lat": {
      "type": "number",
      "format": "double",
      "description": "Station latitude in decimal degrees (WGS84).",
      "minimum": -90,
      "maximum": 90,
      "examples": [37.774]
    },
    "uv": {
      "type": ["number", "null"],
      "description": "UV index value (0–11+ scale).",
      "minimum": 0,
      "examples": [3.0, 8.5]
    },
    "winddir": {
      "type": ["integer", "null"],
      "description": "Wind direction in meteorological degrees (0 = North, 90 = East, 180 = South, 270 = West).",
      "minimum": 0,
      "maximum": 360,
      "examples": [270, 180, 45]
    },
    "windDirectionCardinal": {
      "type": ["string", "null"],
      "description": "Wind direction expressed as a compass cardinal or intercardinal point.",
      "enum": ["N", "NNE", "NE", "ENE", "E", "ESE", "SE", "SSE", "S", "SSW", "SW", "WSW", "W", "WNW", "NW", "NNW", null],
      "examples": ["W", "NNE"]
    },
    "humidity": {
      "type": ["integer", "null"],
      "description": "Relative humidity percentage.",
      "minimum": 0,
      "maximum": 100,
      "examples": [68, 45, 92]
    },
    "epoch": {
      "type": "integer",
      "description": "Unix timestamp (seconds since 1970-01-01T00:00:00Z) of the observation.",
      "examples": [1705343520]
    },
    "qcStatus": {
      "type": "integer",
      "description": "Quality control status flag. 1 indicates the observation passed QC checks.",
      "enum": [-1, 0, 1],
      "examples": [1]
    },
    "realtimeFrequency": {
      "type": ["integer", "null"],
      "description": "Realtime upload frequency in seconds, if the station uploads in realtime mode.",
      "examples": [2.5, null]
    },
    "imperial": {
      "$ref": "#/$defs/unitMeasurements",
      "description": "Measurements in Imperial/US Customary units (°F, mph, inHg, in)."
    },
    "metric": {
      "$ref": "#/$defs/unitMeasurements",
      "description": "Measurements in metric units (°C, km/h, mbar, mm)."
    },
    "metric_si": {
      "$ref": "#/$defs/unitMeasurements",
      "description": "Measurements in SI metric units (°C, km/h, hPa, mm)."
    },
    "uk_hybrid": {
      "$ref": "#/$defs/unitMeasurements",
      "description": "Measurements in UK hybrid units (°C, mph, mbar, mm)."
    }
  },
  "required": ["stationID", "obsTimeUtc", "epoch"],
  "$defs": {
    "unitMeasurements": {
      "type": "object",
      "description": "Weather measurements in a specific unit system.",
      "properties": {
        "temp": {
          "type": ["number", "null"],
          "description": "Air temperature.",
          "examples": [55.0, 12.8]
        },
        "heatIndex": {
          "type": ["number", "null"],
          "description": "Apparent temperature accounting for humidity (feels-like).",
          "examples": [55.0, 12.8]
        },
        "dewpt": {
          "type": ["number", "null"],
          "description": "Dew point temperature.",
          "examples": [44.0, 6.7]
        },
        "windChill": {
          "type": ["number", "null"],
          "description": "Wind chill temperature (perceived temperature with wind effect).",
          "examples": [51.0, 10.5]
        },
        "windSpeed": {
          "type": ["number", "null"],
          "description": "Average wind speed.",
          "minimum": 0,
          "examples": [8.0, 12.9]
        },
        "windGust": {
          "type": ["number", "null"],
          "description": "Peak wind gust speed.",
          "minimum": 0,
          "examples": [12.0, 19.3]
        },
        "pressure": {
          "type": ["number", "null"],
          "description": "Atmospheric pressure (inHg for imperial, mbar for metric).",
          "minimum": 0,
          "examples": [30.05, 1018.0]
        },
        "precipRate": {
          "type": ["number", "null"],
          "description": "Current precipitation rate per hour.",
          "minimum": 0,
          "examples": [0.0, 0.12]
        },
        "precipTotal": {
          "type": ["number", "null"],
          "description": "Accumulated daily precipitation total.",
          "minimum": 0,
          "examples": [0.12, 3.05]
        },
        "elev": {
          "type": ["number", "null"],
          "description": "Station elevation above sea level.",
          "examples": [52.0, 15.85]
        }
      }
    }
  }
}