A process fluid flow system includes a first pipe skin sensor and a second pipe skin sensor. The first pipe skin sensor is disposed to measure an external temperature of a process fluid conduit at a first location on the process fluid conduit. The second pipe skin sensor is disposed to measure an external temperature of a process fluid conduit at a second location on the process fluid conduit. Measurement circuitry is coupled to the first and second pipe skin sensors. A controller is coupled to the measurement circuitry and is configured to identify a process fluid flow condition based on signals from the first and second pipe skin sensors and to output an indication of the process fluid flow condition.