A circuit includes a capacitive-type humidity sensor. The circuit provides start and stop signals to a processor in accordance with a charge voltage across the sensor. The processor performs a counting function to derive an integer count value in response to the start and stop signals. The processor uses the integer count value to determine parameters for controlling an ink-jetting print engine. Printing speed can be controlled in accordance with ambient humidity and/or temperature so that the printed media are sufficiently dried before handling by a user or other operations.