This research paper discusses issues regarding the impact of temperature on the tripping thresholds of intrusion detection system detection circuits. The objective of conducted studies was the verification of a hypothesis assuming that the variability of an intrusion detection system’s (considered as a whole) operating environment temperature can impact the electrical parameters of its detection circuits significantly enough so that it enables a change in the interpretation of the state observed within a given circuit fragment from the state of “no circuit violation” to “circuit violation”. The research covered an intrusion detection system placed in a climatic chamber with adjusted temperature (−25.1 ÷ +60.0 [°C]). The analysis of the obtained results enabled determining the relationships that allow selecting detection circuit resistor values. It is important since it increases the safety level of protected facilities through proper resistor selection, thus, correct interpretation of a detection circuit state.