In 2011, the UK Met Office launched a citizen science project intended to collect data from citizen weather stations (CWS) and, to date, the Weather Observations Website (WOW) project has collected over 1,400 million observations worldwide collected by over 17,000 CWS. The Dutch Met Office (KNMI) joined this project as a partner in 2015 and currently, 500+ CWS monitor the weather in the Netherlands producing over 2 million volunteered weather observations per month.
The European Climate Assessment & Dataset (ECA&D) collects high-quality observational datasets provided by 60+ participant countries. One of the products this organization provides is the E-OBS daily gridded observational dataset, which facilitates the access of the general public to long-term (1950-present) weather gridded layers. The latest release of E-OBS (v20.0) provides data in regular grids for temperature, precipitation, mean sea level pressure and global radiation (newest!), which enable the assessment and analysis of observed changes in climate extremes in Europe.