The microstructure of dry snow corresponds to the complex 3D arrangement of ice and air at the submillimeter scale. Once on the ground, the snow microstructure evolves by sublimation and condensation at the grain interface due to local vapour pressure gradients. These transformations are called dry snow metamorphism. Micro-scale monitoring of these evolutions is key to better understand and model the physical, radiative, and mechanical properties of snow. Here, we present a unique data set consisting of 20 time series of 3D images of dry snow undergoing metamorphism, monitored by X-ray tomography. A wide range of snow evolution conditions was explored: mean snow temperature from -3 to -17°C, snow temperature gradient from 0 to 100 K/m, and five initial snow samples with varying snow type, density, and specific surface area. Each experiment lasted 7 days, and scanning was performed every 4 hours at a spatial resolution of 8.5 µm. The data set comprises 20 videos showing the temporal evolution of the snow microstructure and 20 time series of binary 3D snow images.