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Update - modifies a previous Alert/Update (which is no longer valid)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.

USAGE

/current

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 (CURRENTLY NOT IMPLEMENTED FIXME)

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.

Output format

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.

Experimental GeoJSON format

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.

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

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

Note: This is currently open for testing, but is rather slow and not optimized for full scale use. Do not use this in production environments! If you start sending lots of continous traffic to this service you are liable to get throttled or blocked.

/all (CURRENTLY NOT IMPLEMENTED FIXME)

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

Since updates only refer to the previous alert, you may potentially miss some events if you don't poll the feed regularly. Example:

    [A] <---updated by--- [B] <---cancelled by--- [C]

If you download alert A, but fail to fetch B before it is cancelled by [C], you will have no way of knowing that alert A is no longer valid (unless the time period has elapsed). Therefore you should either delete all previously downloaded alerts when fetching the feed, or use /all to ensure you get all published updates and cancellations.

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

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 is undergoing several changes in the period 2018-2020. For an updated list, please see this dataset from SSB.

lat, lon

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

Note: This feature is experimental, and may be changed without prior notice!

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.

sort

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

area
event
incidentName
t_onset
t_published
type

Example requests (CURRENTLY NOT IMPLEMENTED FIXME)

https://api.met.no/weatherapi/metalerts/2.0/current.rss (RSS feed)
https://api.met.no/weatherapi/metalerts/2.0/current.xml (same output as above, but displayed in browser as XML)
https://api.met.no/weatherapi/metalerts/2.0/current.json (GeoJSON FeatureCollection BETA)
https://api.met.no/weatherapi/metalerts/2.0/current?lang=en
https://api.met.no/weatherapi/metalerts/2.0/all # don't filter out expired alerts
https://api.met.no/weatherapi/metalerts/2.0/current?county=42 (show alerts for Agder county)
https://api.met.no/weatherapi/metalerts/2.0/current?cap=... (check RSS feed above for working URLs)

/Archive/archive

This is used to get historical alerts from the archive, which is segmented by monthly intervals. Currently it only contains data for the period Jan 2019 to Dec 2022, but this updated yearly.

Note: This feature is experimental, and may be changed without prior notice!

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

Test warnings

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=...

Available (CURRENTLY NOT IMPLEMENTED FIXME)

Available is implemented, but shows only CAP files, not RSS feeds. To view historical alerts, use the period parameter. Test warnings are not supported.

https://api.met.no/weatherapi/metalerts/2.0/available.json
https://api.met.no/weatherapi/metalerts/2.0/available.xml?period=2021-01 (reading from archive)

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.

Changelog

Other versions

Supplemental documentation

Alerting colour criteria

Other documents (in Norwegian)

Technical details