Various methods and devices for reducing the time for a body-mountable temperature monitoring device to provide an accurate body temperature are disclosed. Methods are used to accurately predict the measured temperature once the monitoring device reaches thermal equilibrium. For example, in one embodiment, a method for measuring body temperature of a subject includes obtaining, by a temperature monitor attached to a body of the subject, a plurality of body temperature measurements at a plurality of times, determining parameters of a model used for predicting temperature based on the plurality of measurements, predicting a body temperature of the subject based on the model, and outputting the predicted body temperature as a current temperature reading.
