**There is a newer version for this data package:** https://doi.org/10.25678/000GF9 In 2021, the Swiss Federal Office for the Environment (FOEN) tasked Eawag to deploy temperature monitoring stations in several lakes in view of a Swiss-wide temperature monitoring network. The monitoring station in Lake Ägeri (Canton Zug) was introduced in November 2022 and it was operated until the end of 2024 by FOEN (financing) and Eawag (operation and maintenance). The measurement station consists of a profiling sonde, which is recording vertical profiles several times a day. Starting from November 2023, Canton Zug financed a sensor for algae pigment measurements, which was subsequently integrated into the sonde. At the end of 2024, the measurement station was transferred from FOEN to Canton Zug. Since January 2025, the measurement station is operated jointly by Canton Zug (financing), FOEN (financial contribution to data processing and server infrastructure) and Eawag (operation and maintenance). Lake Ägeri has a surface area of 7.2 km2, a maximum depth of around 83 m and is located 724 m a.s.l. The coordinates of the measurement station are: 47.125 N, 8.609 E and the local depth is around 81 m.