Abstract: A temperature monitoring system comprises a sensor for measuring the surrounding temperature, a timer for generating clock data, a controller for reading temperatures at predetermined intervals and storing selected temperature data and corresponding time data in memory, input switches for entering commands and data, a data display, and first and second alarm indicators. The controller operates in predetermined steps to activate the first alarm to indicate a current alarm condition and to activate the second alarm to indicate a past alarm condition. The controller selectively switches the display between normal and alarm modes to show differing time and temperature data depending on the temperature conditions monitored. The user may review alarm histories, including total alarm time and, for each past alarm period, maximum temperature, starting time and alarm duration, which have been calculated and stored.