This dataset contains information about hourly temperature variation, phenotypic and genetic change, and change in environmental parameters in a two-year mesocosm study designed to tease apart the impact that phenotypic plasticity and genetic diversity have on rate of adaptation to experimental heatwaves. All data were collected between 2017 and 2019. Thermal data was collected continuously using data loggers. The frequency of natural heatwaves was manipulated using a programmable aquatic mesocosm facility using data collected from real heatwaves from 2006. Phenotypic evolution was tracked using intermittent common garden life-history studies while changes in clone frequency were determined using microsatellite markers to track changes in clone frequency in manipulated populations over two years. Experimental data on zooplankton community dynamics were monitored using intermittent depth integrated sampling of communities in each mesocosm over two years. The work was supported by the Natural Environment Research Council (Grant NE/N016017/1).