Many datasets provided by the FMI's Open data service can be evaluated visually using the Web Map Service (WMS) interface and an appropriate client software.

The FMI WMS services are not intended as primary means of accessing open data, and the usage is more limited than for the Download service. For example if you wish to use weather radar data in your web or mobile application, you must first download the radar data using the WFS Download service and then provide the radar images to your application yourself. Direct use of the FMI's WMS service for other than evalutation purposes is not allowed because of the high network bandwidth and processing requirements.

If you want to use WMS interface for you client application or provide the FMI Open Data as part of your WMS service your are free to set up your own WMS service. You can provide your own visualisations of FMI Open Data through it as long as you fulfil the terms of the Finnish Meteorological Institute's Open Data Licence. Some of the of the most popular open source WMS servers are Geoserver and MapServer, but there are also a lot of other server applications to choose from.

The basic idea of the OGC Web Map Service (WMS) standard is to provide map image layers

• of the requested data set

• to the requested geospatial area

• in the requested map projection.

A WMS client application can retrieve information about the capabilities of the each service it uses (names of the available layers etc.), and request one ore more map images from those services. The applications typically stack the several map image layers on top of each other to create a map containing layered information.

The mandatory operations for a WMS version 1.3.0 service are:

• GetCapabilities for getting the service metadata, and

• GetMap for getting layer images.

Optionally a WMS 1.3.0 service may also support GetFeatureInfo operation for requesting feature data at a user specified point on the map.

One of the most popular Open Source WMS client implementations for web is OpenLayers, but there are a lot of other options too. For desktop use one of the open source applications is QGIS.