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MetAlerts GeoJSON format

tags: reference - metalerts


The output is a normal GeoJSON FeatureCollection, with each alert as an item in the Features array.

Each feature (alert) has three main parts:

  • geometry: either a Polygon or a MultiPolygon, describing the geographical extent covered
  • properties: various information pertaining to the alert, see below
  • when: time interval when the alert is valid


All the fields have been extracted from the CAP files unchanged unless noted. For more detail, see the CAP v1 and v2 profile docs. All properties indicated in bold should always be present; most of the others are usually not available in CAP v1.

Property Description
altitude_above_sea_level § lower boundary height over mean sea level (WGS84 geoid), in meters †
area general name for the geographical area affected (same as areaDesc in CAP)
awareness_level awareness level, including color
awarenessResponse text describing recommended action/awareness (dependent on severity/certainty)
awarenessSeriousness Text describing seriousness of the situation (dependent on severity/certainty)
awareness_type type of phenomena, according the Meteoalarm classification
ceiling_above_sea_level § lower boundary height over the WGS84 geoid, in meters †
certainty one of “Observed”, “Likely” or “Possible”
consequences consequences of the forecasted weather (related to instructions)
contact URL to a contact information
county an array of county codes (fylkesnr) ‡
description an extended human readable description of the hazard or event
eventAwarenessName Name given severity, certainty and eventType
eventEndingTime the expected end time of the subject event in the alert message
event types of phenomena, see eventCode in the CAP v2 profile for a complete list
geographicDomain area affected, either “land” or “marine”
id the CAP id of the alert (same as identifier in CAP)
incidentName name of incident, normally only given to extreme weather phenomena
instruction recommended actions
municipality an array of municipality codes (kommunenr) ‡
resources additional files available for download, see below
riskMatrixColor § a combinationan of severity and certainty, either Green”, ‘Yellow”, “Orange” or ‘Red”
severity “Extreme”, “Severe”, “Moderate” or “Minor”
status “Actual” or “Test”, indicating if the alert is real or just dummy data
title Short summary of the entire message, giving info about eventType, awareness_level (color), area and valid time (same as headline in CAP)
triggerLevel observed weather will exceed the value specified here during? the indicated time period and area.
type either “Alert” (for new alerts) or “Update” (for replacing existing alerts)
web link to additional or reference information regarding this alert

† Note that this is different from CAP, where the altitude and ceiling is in feet
‡ Same as administrativeId and MunicipalityId in CAP, but formatted for clarity. Only applicable for geographicDomain “land”
§ Only present in CAP v2 profile

Additional properties may be added in the future without further notice.


The resources field links to various external documents with additional data. There will always be a resource named “CAP file” which links to the original data. Other possible resources include maps and other graphics.

Property Description
description caption describing the content of the external resource
mimeType “application/xml” for CAP, usually “image/png” for others
uri link to resource

Example output

  "type": "FeatureCollection"
  "lang": "no",
  "lastChange": "2024-03-05T14:08:36+00:00",
  "features": [
      "geometry": {
        "coordinates": [
            [ 6.3025, 58.2 ],
            [ 6.4088, 58.3058 ],
            [ 6.3185, 58.3302 ],
            [ 6.2137, 58.3592 ],
            [ 6.0827, 58.3988 ],
            [ 5.9707, 58.4442 ],
            [ 5.8422, 58.4987 ],
            [ 5.6927, 58.5687 ],
            [ 5.5955, 58.6587 ],
            [ 5.5248, 58.6458 ],
            [ 5.632, 58.5455 ],
            [ 5.633, 58.5447 ],
            [ 5.635, 58.5432 ],
            [ 5.6767, 58.5157 ],
            [ 5.6777, 58.5152 ],
            [ 5.8387, 58.4185 ],
            [ 5.8398, 58.4178 ],
            [ 5.8508, 58.4118 ],
            [ 5.8527, 58.411 ],
            [ 6.0673, 58.3112 ],
            [ 6.3025, 58.2 ],
            [ 6.3025, 58.2 ]
        "type": "Polygon"
      "properties": {
        "altitude_above_sea_level": "0",
        "area": "Åna-Sira - Obrestad",
        "awarenessResponse": "Følg med",
        "awarenessSeriousness": "Utfordrende situasjon",
        "awareness_level": "2; yellow; Moderate",
        "awareness_type": "1; Wind",
        "ceiling_above_sea_level": "900",
        "certainty": "Observed",
        "consequences": "Sjøen bygger seg opp og det kan være farlig å være ute i småbåt Grov sjø og hvitt skum fra bølgetopper som brekker. ",
        "contact": "",
        "county": [],
        "description": " I dag, tirsdag, fortsatt øst og sørøst stiv kuling 15 m/s, minkende i ettermiddag.",
        "event": "gale",
        "eventAwarenessName": "Kuling",
        "eventEndingTime": "2024-03-05T15:00:00+00:00",
        "geographicDomain": "marine",
        "id": "",
        "instruction": "Vurder å la båten ligge. ",
        "resources": [
            "description": "CAP file",
            "mimeType": "application/xml",
            "uri": "http://localhost:3000/weatherapi/metalerts/2.0/current?cap="
        "riskMatrixColor": "Yellow",
        "severity": "Moderate",
        "status": "Actual",
        "title": "Kuling, gult nivå, Åna-Sira - Obrestad, 2024-03-04T17:00:00+00:00, 2024-03-05T15:00:00+00:00",
        "triggerLevel": "13.9m/s",
        "type": "Update",
        "web": ""
      "type": "Feature",
      "when": {
        "interval": [
—Geir Aalberg, 5 March 2024