FAQ

Below you'll find answers to the most frequently asked questions. We continuously update these based on questions received.

You need to register as a user and authenticate when querying the API’s for several reasons:

• DMI wants to be able to contact users to inform users of planned service windows, breakdowns or new API versions, as well as in give guidance on usage of the API.
• DMI also uses the insight into how data is being used in order to develop new and improved noncommercial services.

Please read the Terms of Use for further information.

In order to retrieve data from our API’s, you need to subscribe to the API’s, which you are interested in. The API-key is linked to the data type (e.g. metObs) and the specific version of the API. The reason for this is that DMI wants to be able to contact the users of the different API’s in order to inform users of planned service windows, breakdowns or new API versions.

Preferably, the email should be linked to the individual/team/service that uses the key.

If it’s for your personal use, you can use a personal email.

If it’s for a service that a team supports, please use an email that that team can access. This way any service announcements from DMI can reach the appropriate persons using the API. This is especially important, if the API is used in a production setting.

In order to receive an API key, you have to register as a user of DMI's API. On the page Authentication you can find a guide on how to register as well as how to find your API key, if you've already registered as a user. 

If you forgot your password, please go to the page Authentication where you can find instructions on how to make a new password.

There is no expiry date on API keys. However, if an API key or a user account has not been used for the past 12 months, it will be deleted.

If you wish to have your API key deleted, you are welcome to contact DMI by using the contact form at https://www.dmi.dk/kontakt/frie-data/ to have your user information deleted, by which your API key will also be deleted.

Please contact us by using the contact form at https://www.dmi.dk/kontakt/frie-data/ and ask to be deleted as a user. We will then deactivate your API key’s and delete the data registered about you. Out of consideration for traceability in relation to information security, deletion will not cover data registered in the logging of requests to DMI’s API’s.

You can access the API specification as well as Request & Response examples and information on data sources by choosing the appropriate data type in the menu on the left side of the screen.

You are able to access the current API documentation by choosing the appropriate data type on the Data page.

DMI’s API's are REST based and thus platform- and language agnostic. Furthermore, as DMI's data are classified as High Value Data, the API's follow OGC-standards.

Unfortunately, it is only possible to query serveral parameters, when using our forecast-EDR-API.

It is not possible to include multiple parameters in a single query in our metObs, oceanObs, climateData, or lightningData API’s. If you want to query more than one parameter in these API’s, you need to query each parameter separately or query all parameters and then filter out the parameters you don’t want afterwards. 

If you want to query multiple stations, you can use a bbox query to do so, if the stations of interest are within the same geographical area. Another option is to query each station separately, or you can query all stations and filter out the stations you don’t want afterwards.

By registering as a user you will automatically receive a notification at the registered email address, when a new version of the API is released.

There is a fair use limit to allow only 500 requests per 5 seconds. If more requests are received a HTTP 429 error is returned. We continuously monitor the use of the API’s and will adjust this limit to ensure, that all users have fair access.

We also recommend using the download functionality, if you want to download large quantities of data. The download functionality is available for the following services: metObs, oceanObs, climateData, and lightningData.

We strive to provide an uptime of the API’s  around 99.9 %.

Downtime is not expected, but in case of planned downtime, it will be announced under API Status & Contact.

The following data is available through the current API's:

• Meteorological Observations Data
• Oceanographic Observations Data
• Lightning Data
• Climate Data
• Radar Data
• Forecast Data (applies to both the Forecast Data STAC-API and Forecast Data EDR API)

You can freely use DMI’s data for any purpose including further processing and distribution. Be aware, that you may not make changes to the actual data retrieved from DMI. Please read the Terms of Use for further information.

Data retrieved from DMI may not be changed. DMI reserves the right to block or adjust the bandwidth for individual users, if these strain DMI’s API's to a disproportionately wide extent.

You can see the update frequency by choosing the appropriate data type on the Data page and then choosing “Parameters”.

Please note that lightning data does not have a specific update frequency, since the data is updated in real time.

If you want to download large quantities of historical data, we recommend that you use download. This lets you download .zip files, each containing historic data for a month or year. You are also able to download all historic data by selecting the file all.zip. Files contain the same data as in the API and are updated hourly.

DMI’s open data is retrieved in JSON format (”JavaScript Object Notation”). JSON is a compact file format for the exchange of data. JSON is a text format which is platform- and language agnostic and which can be read by humans as well as machines. The JSON format can easily be converted to other file formats such as .csv or .xml.

All API's return GeoJSON (external site) for query responses and the downloaded files from Radar and Forecast APIs are in HDF5 and GRIB format, respectively.

Data retrieved through the API is only available in JSON format, but DMI's open data can easiliy be imported directly into GIS. Please see our guide.

For QGIS there is a plugin called "DMI Open Data", that can be used to easily import data. Please see our guide.

Data from our OGC API-features services (metObs, oceanObs, lightningdata and climateData) can be imported into excel. Please see our guide.

Observation data have not been subject to quality control nor processed in any way. Errors in measurements may occur. Errors are typically due to malfunction of instruments caused by wear and tear or exposure to weather and in some cases seawater and on rare occasions from vandalism. Wear and tear of the instruments are handled proactively by performing service checks at the stations on a regular basis and changing the instruments within the given time frame. Due to this, you have to be aware of the risk of faulty measurements when using DMI’s observation data.

It is possible to download data from third parties through the DMI API, if an agreement exists between the third party and DMI. The owner of the station is marked in the station list of the service.

If you have questions regarding data from third parties, please contact the authority responsible for the specific station or the data derived therefrom.

The data retrieved through DMI's Open Data API correlates to the data available to DMI. Sometimes you may experience that some data entries are missing. The root cause of this is typically a malfunctioning measurement instrument, which DMI will repair as soon as possible.

The coordinate datum used for the location of the stations is WGS84.

The 1x1 km grid is used as an intermediate basis to construct the spatial resolutions 10x10 km, 20x20 km, municipality data and country data. Under certain weather conditions the 1x1 km grid data can be quite imprecise, but by aggregating it to larger areas the uncertainty is reduced. Furthermore, 3^rd party data, which DMI doesn’t have permission to redistribute, can be deducted directly from the 1x1 km grid data.

If you have questions regarding data, please contact the authority responsible for the specific station or the data derived therefrom.

You can see the owner of a station by selecting the appropriate data type on the Data page and then choosing “Stations” and then clicking the link for the station list.

In the radar forecast on dmi.dk we use Gunnar Farnebäck's dense optical flow algorithm as implemented in OpenCV: https://docs.opencv.org/3.4/de/d9e/classcv_1_1FarnebackOpticalFlow.html (external site).

We also use a range of other methods (e.g. Lucas-Kanade optical flow) available in pySTEPS: https://pysteps.readthedocs.io (external site).

Radar data on dmi.dk is a special product that only shows the lowest elevation scan which is gathered every 5 minutes. This data is currently not a part of DMI’s open data service.

You can report errors by using the contact form at https://www.dmi.dk/kontakt/frie-data/

If you have questions regarding data from third parties, please contact the authority responsible for the station or the data derived therefrom.

If you are experiencing that the API is out of service please check the API status page or contact The Agency for Governmental IT Services (SIT - Statens It).

Call SIT: +45 72 31 00 01