Plynlimon stream water temperatures 1983-2018

Manual measurement of water temperature, made when a water sample is taken for chemical analysis. Thermometer is placed in the stream and a value is recorded once the reading has stabilised. Missing values indicate no temperature measurement was made when the water sample was taken. Various handheld thermometers have been used over the years. Frequency of measurements varies from weekly to monthly. From the early 1980s to December 2011 recording was weekly. Recording was reduced to once every two weeks, starting in January 2012, and was reduced further to once every month in October 2017.