Purpose <p>Given the limited research on radon-related risks and migration mechanisms in frozen soils of cold regions, this study investigates the impact of temperature(ranging from − 20&#xa0;°C to 0&#xa0;°C) and initial water content on the radon emanation coefficient of frozen silty clay.</p> Materials and methods <p>Radon concentrations in frozen silty clay were measured under various thermo-hydro conditions. The soil’s radon emanation coefficient was then calculated based on these measurements.</p> Results and discussion <p>The results show that the radon emanation coefficient of frozen silty clay is significantly influenced by both temperature and initial water content. Specifically, the coefficient initially increases but tends to stabilize or decrease as initial water content increases, in contrast to the strong linear relationship observed with temperature. Furthermore, within the temperature range of -15&#xa0;°C to -5&#xa0;°C, the maximum sensitivity of the coefficient is typically observed during the rapid ice-water phase transition.</p> Conclusions <p>This study provides valuable insights into the processes of radon migration and emanation in frozen soils. The findings have important implications for understanding radon behavior in cold regions, contributing to environmental risk assessment and public health protection in the context of a changing climate.</p>