A method for determining the ambient temperature of an electronic device, the device comprising heat-generating components (102) and a temperature sensor (105) positioned within a common casing (101), the method comprising the steps of: in an environment with a controlled ambient temperature: determining (307) a device-specific coefficient of power dissipation change (a) between a first (Emin) and second (Emax) power modes, wherein in the second power mode (Emax) the device dissipates more power than in the first power mode (Emin); and in an environment for which the ambient temperature is to be determined: measuring (203-205) temperatures (Tmin, Tmax) by the temperature sensor (105) for the first power mode (Emin) and the second power mode (Emax), calculating (206) ambient temperature (Tamb) as a function of the measured temperatures (Tmin, Tmax) and the device-specific coefficient of power dissipation change (a).