# Severe Weather Sample

This page provides a complete sample response for a severe weather hazard from the Active Hazards API endpoint. Severe weather hazards encompass a broad category of weather alerts including dense fog warnings, special weather statements, severe thunderstorm warnings, and general severe weather advisories issued by national meteorological services. These alerts may follow the Common Alerting Protocol (CAP) standard or use agency-specific formats such as those from the China Meteorological Administration (CMA).

## Severe Weather-Specific Properties

### Incident Data

The `incident.properties` object for a severe weather hazard contains standard alert metadata. Key incident properties include:

* `senderName` - Issuing agency (e.g., `"China Meteorological Administration"`)
* `headline` - Alert headline text (e.g., `"Heavy fog — Orange Warning (Level II) for Chongming District..."`)
* `description` - Detailed alert description with forecast information and expected impacts
* `severity` - Severity level (e.g., `"Severe"`)
* `urgency` - Urgency level (e.g., `"Unknown"`)
* `certainty` - Certainty level (e.g., `"Unknown"`)
* `event` - Event type name (e.g., `"Dense Fog"`)
* `effective` / `expires` / `onset` - ISO 8601 timing fields for the alert window
* `msgType` - Message type (e.g., `"Update"`)
* `instruction` - Recommended actions (may be empty for some alerts)
* `category` - Category (e.g., `"Met"` for meteorological)
* `hazardSeverity` - Hazard severity classification (e.g., `"WATCH"`)
* `incidentLocationName` - Human-readable location (e.g., `"Nantong, Jiangsu, China"`)
* `headlineDescription` - Full descriptive headline combining alert status and forecast details

### Features

The `features` property contains a GeoJSON FeatureCollection with `EXPOSURE_AREA` and `SMART_ALERT` features. For CMA-sourced alerts, features include exposure area polygons with severity levels and exposure level indicators rather than CAP\_INFO features. The collection may contain multiple exposure area features at different severity levels (e.g., MODERATE, STRONG).

### Exposure Areas

Severe weather hazards may use multiple exposure levels representing different severity zones:

* **Level 1**: Moderate exposure area - outer zone with lower expected impact
* **Level 2**: Strong exposure area - core zone with highest expected impact

## Sample Response

```json
{
  "name": [
    {
      "locale": "en",
      "value": "Dense Fog - Nantong, Jiangsu, China"
    }
  ],
  "description": [
    {
      "locale": "en",
      "value": "China Meteorological Administration has issued a Dense Fog watch for March 12, 2026 21:41:00 UTC through March 14, 2026 01:53:02 UTC.\n\nIt is estimated that 6.71 Million people, 2.43 Million households, and $171 Billion (USD) of infrastructure* are within the affected area(s). Exposure estimates will be refined as additional data from official sources becomes available.\n\nAt 05:41 on March 13, 2026, Chongming District Meteorological Observatory issued an orange (Level II) heavy fog warning: widespread heavy fog with visibility expected below 200 meters in most towns and villages, and locally below 50 meters..."
    }
  ],
  "severity": "WATCH",
  "category": "EVENT",
  "incident": {
    "uuid": "a0ab1db9-175e-43f9-a06b-07c51ea0224c",
    "type": "SEVEREWEATHER",
    "sourceId": 1797,
    "sourceRecordId": "31015141600000_20260313040908",
    "properties": {
      "hazardName": "Dense Fog - Nantong, Jiangsu, China",
      "senderName": "China Meteorological Administration",
      "urgency": "Unknown",
      "headline": "Heavy fog — Orange Warning (Level II) for Chongming District and parts of Nantong; warning status updates in Zhangjiagang, Changshu, Haimen and Nantong",
      "severity": "Severe",
      "certainty": "Unknown",
      "status": null,
      "..."
    }
  },
  "uuid": "67cc5de8-daf6-4690-be4a-60c417476108",
  "comment": null,
  "createdAt": 1773366783,
  "relatedHazards": [],
  "longitude": 120.92874,
  "latitude": 32.19687,
  "version": 8,
  "alertGeometry": {
    "type": "FeatureCollection",
    "features": [
      {
        "type": "Feature",
        "geometry": {
          "type": "MultiPolygon",
          "coordinates": [...]
        },
        "properties": {}
      }
    ]
  },
  "features": {
    "features": [
      {
        "id": null,
        "type": "Feature",
        "properties": {
          "severity": "STRONG",
          "exposureDescription": "STRONG",
          "featureType": "EXPOSURE_AREA",
          "exposureLevel": 2
        },
        "geometry": {
          "type": "MultiPolygon",
          "coordinates": [...]
        },
        "incidentType": null,
        "sourceId": null
      },
      {
        "id": null,
        "type": "Feature",
        "properties": {
          "featureType": "SMART_ALERT"
        },
        "geometry": {
          "type": "MultiPolygon",
          "coordinates": [...]
        },
        "incidentType": null,
        "sourceId": null
      }
    ],
    "incidentType": null,
    "metadata": null,
    "type": "FeatureCollection",
    "sourceId": null
  },
  "exposureAreas": {
    "type": "FeatureCollection",
    "features": [
      {
        "type": "Feature",
        "geometry": {
          "type": "MultiPolygon",
          "coordinates": [...]
        },
        "properties": {
          "exposureLevel": 2
        }
      },
      {
        "type": "Feature",
        "geometry": {
          "type": "Polygon",
          "coordinates": [...]
        },
        "properties": {
          "exposureLevel": 1
        }
      }
    ]
  },
  "exposureAssessment": {
    "population": {
      "total": 6710000,
      "total0_14": 1113189,
      "total15_64": 4636610,
      "total65_Plus": 961543,
      "households": 2431159,
      "vulnerable": 261000
    },
    "capital": {
      "total": 171710057000,
      "school": 9,
      "hospital": 25
    },
    "totalByCountry": [
      {
        "population": {
          "total": 6710000,
          "total0_14": 1113189,
          "total15_64": 4636610,
          "total65_Plus": 961543,
          "households": 2431159,
          "vulnerable": 261000
        },
        "country": "CHN",
        "capital": {
          "total": 171710057000,
          "school": 9,
          "hospital": 25
        },
        "admin0": "China",
        "admin1": null,
        "admin2": null,
        "foodNeedsUnit": "CAL",
        "foodNeeds": 548100000.0,
        "waterNeedsUnit": "liter",
        "waterNeeds": 783000.0,
        "wasteNeedsUnit": "100 liter",
        "wasteNeeds": 26100.0,
        "shelterNeedsUnit": "sq meters",
        "shelterNeeds": 900450.0
      }
    ],
    "totalByAdmin": [
      {
        "population": {
          "total": 6710000,
          "total0_14": 1113189,
          "total15_64": 4636610,
          "total65_Plus": 961543,
          "households": 2431159,
          "vulnerable": 261000
        },
        "country": "CHN",
        "capital": {
          "total": 171710057000,
          "school": 9,
          "hospital": 25
        },
        "admin0": "China",
        "admin1": null,
        "admin2": null,
        "foodNeedsUnit": "CAL",
        "foodNeeds": 548100000.0,
        "waterNeedsUnit": "liter",
        "waterNeeds": 783000.0,
        "wasteNeedsUnit": "100 liter",
        "wasteNeeds": 26100.0,
        "shelterNeedsUnit": "sq meters",
        "shelterNeeds": 900450.0
      }
    ],
    "exposureLevels": [
      {
        "level": "1",
        "data": {
          "population": {
            "total": 657000,
            "total0_14": 108996,
            "total15_64": 453987,
            "total65_Plus": 94148,
            "households": 238043,
            "vulnerable": 25600
          },
          "capital": {
            "total": 15821398300,
            "school": 0,
            "hospital": 2
          },
          "totalByCountry": [
            {
              "population": {
                "total": 657000,
                "total0_14": 108996,
                "total15_64": 453987,
                "total65_Plus": 94148,
                "households": 238043,
                "vulnerable": 25600
              },
              "country": "CHN",
              "capital": {
                "total": 15821398300,
                "school": 0,
                "hospital": 2
              },
              "admin0": "China",
              "admin1": null,
              "admin2": null,
              "foodNeedsUnit": "CAL",
              "foodNeeds": 53760000.0,
              "waterNeedsUnit": "liter",
              "waterNeeds": 76800.0,
              "wasteNeedsUnit": "100 liter",
              "wasteNeeds": 2560.0,
              "shelterNeedsUnit": "sq meters",
              "shelterNeeds": 88320.0
            }
          ],
          "totalByAdmin": [
            {
              "population": {
                "total": 657000,
                "total0_14": 108996,
                "total15_64": 453987,
                "total65_Plus": 94148,
                "households": 238043,
                "vulnerable": 25600
              },
              "country": "CHN",
              "capital": {
                "total": 15821398300,
                "school": 0,
                "hospital": 2
              },
              "admin0": "China",
              "admin1": null,
              "admin2": null,
              "foodNeedsUnit": "CAL",
              "foodNeeds": 53760000.0,
              "waterNeedsUnit": "liter",
              "waterNeeds": 76800.0,
              "wasteNeedsUnit": "100 liter",
              "wasteNeeds": 2560.0,
              "shelterNeedsUnit": "sq meters",
              "shelterNeeds": 88320.0
            }
          ],
          "foodNeedsUnit": "CAL",
          "foodNeeds": 53760000.0,
          "waterNeedsUnit": "liter",
          "waterNeeds": 76800.0,
          "wasteNeedsUnit": "100 liter",
          "wasteNeeds": 2560.0,
          "shelterNeedsUnit": "sq meters",
          "shelterNeeds": 88320.0
        },
        "exposureDescription": "MODERATE"
      },
      {
        "level": "2",
        "data": {
          "population": {
            "total": 6050000,
            "total0_14": 1003695,
            "total15_64": 4180550,
            "total65_Plus": 866965,
            "households": 2192029,
            "vulnerable": 235000
          },
          "capital": {
            "total": 155888658700,
            "school": 9,
            "hospital": 23
          },
          "totalByCountry": [
            {
              "population": {
                "total": 6050000,
                "total0_14": 1003695,
                "total15_64": 4180550,
                "total65_Plus": 866965,
                "households": 2192029,
                "vulnerable": 235000
              },
              "country": "CHN",
              "capital": {
                "total": 155888658700,
                "school": 9,
                "hospital": 23
              },
              "admin0": "China",
              "admin1": null,
              "admin2": null,
              "foodNeedsUnit": "CAL",
              "foodNeeds": 493500000.0,
              "waterNeedsUnit": "liter",
              "waterNeeds": 705000.0,
              "wasteNeedsUnit": "100 liter",
              "wasteNeeds": 23500.0,
              "shelterNeedsUnit": "sq meters",
              "shelterNeeds": 810750.0
            }
          ],
          "totalByAdmin": [
            {
              "population": {
                "total": 6050000,
                "total0_14": 1003695,
                "total15_64": 4180550,
                "total65_Plus": 866965,
                "households": 2192029,
                "vulnerable": 235000
              },
              "country": "CHN",
              "capital": {
                "total": 155888658700,
                "school": 9,
                "hospital": 23
              },
              "admin0": "China",
              "admin1": null,
              "admin2": null,
              "foodNeedsUnit": "CAL",
              "foodNeeds": 493500000.0,
              "waterNeedsUnit": "liter",
              "waterNeeds": 705000.0,
              "wasteNeedsUnit": "100 liter",
              "wasteNeeds": 23500.0,
              "shelterNeedsUnit": "sq meters",
              "shelterNeeds": 810750.0
            }
          ],
          "foodNeedsUnit": "CAL",
          "foodNeeds": 493500000.0,
          "waterNeedsUnit": "liter",
          "waterNeeds": 705000.0,
          "wasteNeedsUnit": "100 liter",
          "wasteNeeds": 23500.0,
          "shelterNeedsUnit": "sq meters",
          "shelterNeeds": 810750.0
        },
        "exposureDescription": "STRONG"
      }
    ],
    "hazardUuid": "",
    "hazardType": "",
    "version": "",
    "timestamp": "1773366775760",
    "exposureDescription": "",
    "foodNeedsUnit": "CAL",
    "foodNeeds": 548100000.0,
    "waterNeedsUnit": "liter",
    "waterNeeds": 783000.0,
    "wasteNeedsUnit": "100 liter",
    "wasteNeeds": 26100.0,
    "shelterNeedsUnit": "sq meters",
    "shelterNeeds": 900450.0
  },
  "type": "SEVEREWEATHER",
  "creator": "RICHTER",
  "source": null,
  "startedAt": 1773351660,
  "updatedAt": 1773366775,
  "endedAt": 1773453182
}
```

{% hint style="info" %}
Note: Coordinate arrays have been replaced with `[...]` for brevity. In actual API responses, these contain complete GeoJSON coordinate arrays. The `incident.properties` object has been truncated with `"..."` to show only key fields. The full response includes additional metadata fields. This sample shows a CMA-sourced dense fog alert from China, which uses a different property structure than CAP-based alerts from Environment Canada or BoM. The `features` collection contains EXPOSURE\_AREA features at different severity levels and a SMART\_ALERT feature. The description field includes summarized content from multiple active alerts issued across the affected region.
{% endhint %}


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