This dataset provides borehole ground temperature data recorded at three drilling mud sumps in the Northwest Territories of Canada as part of the project “Thawing industrial legacies in the ArctIc - a threat to permafrost ecosystems (ThinIce)”. The dataset consists of eight individual .csv files, each representing a borehole equipped with temperature sensors. Each file contains hourly ground temperature measurements recorded at multiple depths. The ground temperature data were collected using continuously recording sensors between 2024 and 2025, while one borehole at mud sump Kamik F38 includes earlier records starting in 2021, see table below. Additional information about the installed sensors and the location of the boreholes is provided in the file borehole_sensors-locations.csv Borehole date_start date_end Kamik_F38_CS-1 09/09/21 08/06/25 Kamik_F38_H3-1 8/16/24 7/17/25 Kamik_F38_H3-4 08/29/24 08/06/25 Parsons_E02_C 08/11/24 08/27/25 Parsons_E02_H1-1 08/12/24 08/27/25 Parsons_E02_H1-4 08/14/24 08/27/25 TukTuk_A12_C 08/20/24 08/28/25 TukTuk_A12_S1 08/21/24 08/28/25