This is part of a long-term monitoring dataset from fortnightly sampling at the North Basin of Windermere in Cumbria, England. The data have been collected by the UK Centre for Ecology & Hydrology (UKCEH). The data available to download comprise hypolimnion temperature (TEMP) in degree Celsius, and hypolimnion dissolved oxygen concentration (DO) in mg per litre. All data have been measured in a depth of 60 to 62 m. All data are from January 2005 until the end of 2009. 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. Full details about this dataset can be found at https://doi.org/10.5285/83aece7c-6ff0-4414-87ce-71ba27083b92