This dataset consists of hourly lake temperature, air temperature, solar irradiance and wind speed data from an automatic water monitoring buoy on Blelham Tarn, a lake in the North West of England. The lake temperatures are measured at 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 and 12 m depth (see supporting documentation for more information). Measurements were taken every four minutes and calculated as hourly averages. All data is given in GMT (Greenwich Mean Time). The data were collected by the UK Centre for Ecology & Hydrology. This work was supported by the Natural Environment Research Council award number NE/R016429/1 as part of the UK-SCAPE programme delivering National Capability.