Hydrodynamic modeling of lakes requires an extensive amount of data that must often be measured far from the shore and throughout the water column. Accordingly, long-term comprehensive data sets for lakes are relatively rare. Lake Iseo is a deep prealpine lake, which we have monitored since 1995 on a monthly basis, collecting high-resolution data since 2011. These measurements were complemented with additional time series from surrounding meteorological stations and a comprehensive data set has been gathered for the period 1995–2012. This can be used, among other things, to test the capabilities of models to investigate the dynamics of a deep lake.