Atmospheric radon concentrations were monitored from autumn 2004 to winter 2007 in an abandoned coal mining area of SW Poland that contained various bedrock uranium contents, ranging from 1 to 8 ppm. Gamma spectrometric measurements of eU, eTh and K content in the bedrock were combined with radon-monitoring results at 77 points, obtained via Kodak LR-115 detectors. The average atmospheric radon concentration was high (70 Bq m^–3), reaching its maximum in the tailing area (131 Bq m^–3). Strong spatial and seasonal variations in atmospheric radon concentrations were observed. Spatial variations were correlated with changing basement uranium content. Seasonal changes were positively correlated with temperature and negatively with humidity, resulting in maximum atmospheric radon activity in the summer. The strong influence of local basement uranium content indicates its importance in planning monitoring campaigns.