WMO Hydrological Observing System
WHOS is a portal to the online holdings of National Hydrological Services (NHS) around the world that publish their historical (OBS) and/or real-time (RT) data without restrictions or cost. It represents the hydrological component of the WMO Integrated Global Observing System (WIGOS).
Access to the data comprising WHOS can be obtained via map-based links on the following map. Green dots appear in countries where the National Hydrological Service (NHS) makes data available from its website. Red dots appear in countries where the National Hydrological Service has a website, but where hydrological data are not available.
Please note that NHS websites appear in the native language of the country, although some NHSs translate parts or all of their websites into English or other languages.
Organization/Institution providing links to data
Organization/Institution without links to dataImportant Notes: WHOS is being developed and implemented in phases. The map interface appearing above is a provisional product designed for demonstration and testing in preparation for a review of the WHOS concept at the 15th Session of the Commission for Hydrology (CHy-15) in December 2016. A full WHOS implementation is subject to approval by CHy-15.
The information contained on this map is continuously being updated as more National Hydrological Services make their data available online. Links to the data of National Hydrological Services not appearing on this map, as well as incorrect information or broken links, should be reported to WMO via email at
.