A method and apparatus for estimating a body temperature and/or an ambient air temperature and/or blood flow. The method and apparatus acquire values indicative of temperature from two or more sensors. Some of the sensors being in thermal contact with a surface of the body and the other sensors being in thermal contact with the ambient air. A transfer function is then applied to the values from the sensors in order to form an estimate of the body temperature and/or the ambient air temperature and/or blood flow. The transfer function is indicative of a thermal relationship between the body temperature, the values of the sensors, the ambient air temperature and the blood flow.