Metalerts

This version (2.0) is currently in beta and should not yet be used in production.

NAME

MetAlerts - Weather alerts from the Norwegian Meteorological Institute

DESCRIPTION

This service provides meteorological warnings in CAP format, as well as a listing of current warnings in an RSS 2.0 feed. Both are in XML format, but there is an experimental GeoJSON version in beta.

Alerts are issued on three levels:

Red - Extreme weather with over 50 % probability. These will normally have an issued name, look for incidentName in the CAP file
Orange - Severe weather, or extreme weather with less than 50 % probability
Yellow - Less severe weather, or severe with less than 50 % probabilty

Each CAP message is one of the following types, as indicated in the msgType value:

Alert - warning about a new phenomenon
Update - modifies a previous Alert/Update (which is no longer valid)
Cancel - invalidates a previous Alert/Update

For more information on the CAP format and meanings, see the "other resources" tab.

Output formats

XML

Unless the cap parameter is given, we return an RSS 2.0 feed of alerts.

Tip: Many browsers have removed RSS support and insist on downloading RSS feeds to disk despite being perfectly able to display XML. To avoid this, you can indicate .xml as output format, which will return the corresponding MIME type so it can be displayed in the browser:

https://api.met.no/weatherapi/metalerts/2.0/current.xml

GeoJSON format (beta)

Due to user feedback we are working on a supplemental GeoJSON format, where all relevant information is included without the need to open separate CAP files. This is currently considered a beta feature, and not suitable for high volume production as it is rather slow and costly to produce. We do not plan to make any more changes to the GeoJSON format in version 2.0; an official GeoJSON format may possibly be added later in 2024.

https://api.met.no/weatherapi/metalerts/2.0/current.json

This also works for other methods, like all, test, archive and so on.

Icons

You can download alerting icons in SVG format (which can be converted to PNG) from the Yr GitHub page:

https://github.com/nrkno/yr-warning-icons

In the future this icon set will be migrated to the Weathericons GitHub repo as currently used with Locationforecast.

USAGE

Methods

/current - show active alerts

Use the RSS feed to get a list of CAP warnings, optionally filtered by query parameters.

https://api.met.no/weatherapi/metalerts/2.0/current.rss
https://api.met.no/weatherapi/metalerts/2.0/current.xml
https://api.met.no/weatherapi/metalerts/2.0/current.json

Do not download each CAP file more than once, and certainly not every time you download the RSS feed! (this is liable to getting you throttled). Once issued the CAP file never changes, so it should be downloaded only once and stored locally.

/all - show active and inactive alerts

Normally only active alerts are listed, with expired alerts filtered out. Using /all will list all alerts issued during the last 30 days, both active and inactive.

https://api.met.no/weatherapi/metalerts/2.0/all.rss
https://api.met.no/weatherapi/metalerts/2.0/all.xml
https://api.met.no/weatherapi/metalerts/2.0/all.json

/archive - historical alerts

This is used to get historical alerts from the archive, which is segmented by monthly intervals. Currently it contains data for the period Jan 2019 to Dec 2023; new periods are added at the start of each year.

Note: All alerts prior to May 2024 follows the v1 CAP profile.

https://api.met.no/weatherapi/metalerts/2.0/archive?period=2022-02

/test - Test alerts

Meteorologists sometimes want to test fictional CAP warnings to check that they work upstream. These can be accessed via RSS at the /test endpoint:

https://api.met.no/weatherapi/metalerts/2.0/test.rss
https://api.met.no/weatherapi/metalerts/2.0/test.json
https://api.met.no/weatherapi/metalerts/2.0/test?cap=...

/example - Examples of different alerts

These are examples of test alerts, one for each event type (currently forestFire, blowingSnow, rainFlood, lightning and rainFlood). These don't expire until 2034, so will be available for use in development testing for years to come.

https://api.met.no/weatherapi/metalerts/2.0/example.rss
https://api.met.no/weatherapi/metalerts/2.0/example.json
https://api.met.no/weatherapi/metalerts/2.0/example?cap=...

Parameters

cap

Retrieve CAP XML message with given guid

lang

Output language, currently "no" or "en" for Norwegian and English, respectively

event

Filter by CAP eventType, legal values are: blowingSnow, forestFire, gale, ice, icing, lightning, polarLow, rain, rainFlood, snow, stormSurge, wind

You can find matching icons (SVG and PNG) for all events on the Yr warning icons repo.

incidentName

Filter by incident (names given to red alert extreme weather phenomena)

geographicDomain

Filter by land or marine

county (fylke)

Filter by Norwegian county number where available (only land areas, not gale warnings etc). The county number is defined as always having 2 digits, so the counties Østfold to Aust-Agder must be zero prefixed. Currently one single county allowed per request.

Note that the list of counties has changed several times during the 2018-2024 period. For an updated list, please see this dataset from SSB.

lat, lon

Coordinates for geographical search (returns all alerts covered by the search location)

period

Only used with the /archive method. Use ISO format for months, on the form YYYY-MM. Periods outside the archive timespan will return error. Legal values are: 2019-01, 2019-02, 2019-03, 2019-04, 2019-05, 2019-06, 2019-07, 2019-08, 2019-09, 2019-10, 2019-11, 2019-12, 2020-01, 2020-02, 2020-03, 2020-04, 2020-05, 2020-06, 2020-07, 2020-08, 2020-09, 2020-10, 2020-11, 2020-12, 2021-01, 2021-02, 2021-03, 2021-04, 2021-05, 2021-06, 2021-07, 2021-08, 2021-09, 2021-10, 2021-11, 2021-12, 2022-01, 2022-02, 2022-03, 2022-04, 2022-05, 2022-06, 2022-07, 2022-08, 2022-09, 2022-10, 2022-11, 2022-12, 2023-01, 2023-02, 2023-03, 2023-04, 2023-05, 2023-06, 2023-07, 2023-08, 2023-09, 2023-10, 2023-11, 2023-12.

sort

Sort RSS items on field (in ascending order). The following fields are available:

area
event
incidentName
t_onset
t_published
type

Example requests

https://api.met.no/weatherapi/metalerts/2.0/current.rss?lang=en
https://api.met.no/weatherapi/metalerts/2.0/all.xml?county=42 (show alerts for Agder county)
https://api.met.no/weatherapi/metalerts/2.0/current.xml?cap=... (check RSS feed above for working URLs)

Changelog

2024-03-07

Several new properties added to GeoJSON output:

status (Actual eller Test)
municipality (kommunenr)
web
contact
description (for resources, previously broken)
altitude (feet above msl)
ceiling (feet above msl)

Changelog

Other versions

Supplemental documentation

Output format descriptions

Alerting colour criteria

Other documents (in Norwegian)

Technical details