Description: Permafrost around the Arctic is warming and thawing. We report data from the high arctic research site Bayelva (78.551N; 11.571E) located close to Ny-Alesund. Data on meteorology, energy balance components and subsur- face observations have been made for the last 20 years (1998-2017; Boike et al. 2017). This study site is underlain by permafrost with current mean permafrost temperature of -2.8◦C and is seasonally snow-covered from October to May. Mean annual, summer and winter soil temperature data at all depths have beenrising over the period of record with a warming trend of 0.18±0.07◦C/year in active layer and top of permafrost. However, interannual to sub-decadal variability is evident in the data and results mostly from differences of theclimate during the winter months. The modeled active layer thickness using the Stefan equation has increasedcontinuously from about 1m in 1998 and is estimated to have surpassed 2 m in 2016. The data show that snow ablation has started earlier, thus extending the snow free season, potentially re-sulting in more time for soil warming and deepening of active layer. The snow cover onset and ablation, aswell as the thermo insulation properties of the snow cover, will be investigated together with active layer and permafrost variables (temperature, volumetric water content) for further understanding of the observed warming and deepening. Boike, J., Juszak, I., Lange, S., Chadburn, S., Burke, E., Overduin, P. P., Roth, K., Ippisch, O., Bornemann, N., Stern, L., Gouttevin, I., Hauber, E., and Westermann, S.: A 20-year record (1998–2017) of permafrost, active layer and meteorological conditions at a high Arctic permafrost research site (Bayelva, Spitsbergen), Earth Syst. Sci. Data, 10, 355-390, https://doi.org/10.5194/essd-10-355-2018, 2018.