This letter focuses on the remote reading of high-resolution microfluidic and passive (i.e., batteryless and chipless) temperature sensors. These sensors are remotely interrogated from a 24GHz Frequency-Modulated Continuous-Wave radar performing a mechanical beam scanning for locating the sensors and measuring the variation of sensors electromagnetic echo level due to temperature fluctuation. From radar measurement data an estimator is proposed here for determining the meniscus position of the fluid inside the sensors microchannel and for deriving the temperature at the sensors location. It is shown that the estimator presents a convenient linear dependence with the meniscus position at the sensor location. The smallest measurable variation of the meniscus position is of 40µm.