Never leave a thermometer inside an oven, grill, smoker, or microwave while cooking unless it is specifically designed for this. Although some probes are designed to be left inside an oven or grill it is important to not leave your thermometer on the grill hood or close to an open flame. The housing itself (where the electronic components are kept) typically needs to be kept cool and should only be brought near heat for short periods of time so that the unit does not overheat.