Radon concentrations in soil gas were continuously measured by the LR-115 nuclear track detectors during four years. Also seismic activities, as well as the barometric pressure, rainfall and air temperature were observed. The influence of the meteorological parameters to the temporal radon variations was investigated and the respective equation of the multiple regression was derived. The earthquakes with magnitude ≥ 3 at epicentral distances ≤ 200 km were recognized by means of the radon anomaly. Empirical equations between the earthquake magnitude, epicentral distance and precursor time were examined, and respective constants were determined.