The wearable device incorporates a device for measuring the ambient temperature, which comprises an infrared sensor. In an ambient temperature measurement mode a control circuit activates the infrared sensor several times so that it can supply a plurality of measurement signals over a certain period of time. A circuit for processing measurement signals is then arranged in order to supply temperature values corresponding to at least a portion of the measurement signals and to take a mean for at least a portion of these temperature values to obtain an average temperature value that is considered to be representative of the ambient temperature. The invention also relates to a method for measuring the ambient temperature that can be implemented by means of this wearable device.