Fracturing a well can include disposing within the well a plurality of temperature responsive devices including a trigger circuit. The devices may be configured to establish fluid communication through a casing of the well or isolate a section of the well responsive to a downhole temperature, a number of downhole temperature cycles, and/or a time delay. The devices may operate by triggering an explosive and/or initiating at least one of a thermal, incendiary, or chemical cutting device. The devices can perforating sleeves adapted to be installed over a casing joint, subs adapted to be threaded between two casing joints, perforating devices embedded within a casing joint, isolation mechanisms, or toe valves.