In recent years, there has been a debate in the scientific literature about the possibility of variability in the rate of radioactive decay under the influence of external factors, as evidenced by separate experiments. However, since such effects are in sharp conflict with the basic principles of nuclear physics, there is also a strong criticism, which converges to that all such experiments are incorrect. At the same time, one way or another, everything converges to that the observed effects are the result of the response of the measurement equipment to external weather conditions, that is, caused by changes in temperature, humidity, etc. And these effects are not changes of the actual measured physical quantity. In this work, the possibility of influence of such a factor as temperature is carefully considered. A correlation was found between regular series of measurements of temperature and gamma background level in the exclusion zone of the Chornobyl nuclear power plant, which is contaminated by fuel fallouts from the destroyed power unit. The assumption was made regarding the mechanism of formation of features in gamma background signals. The revealed relation may indicate the existence of a common global factor (cause) of the variability of the gamma background signals and temperature, which should be sought beyond trivial assumptions about the influence of meteorological conditions on the operation of the equipment.