High-precision temperature sensor is demonstrated based on weak measurement using spectrum domain analysis. By introducing an extra phase to the postselection, the operating temperature range and temperature precision can be conveniently modulated. Spectral shifts resulted from temperature variation are robust to practical imperfections. The precision of 2.4 × 10-6°C can be achieved by a currently available spectrometer. The maximum operating range is associated with the nematic temperature range of nematic liquid crystals (NLCs) sample. Moreover, the temperature sensitivity of 16.16 nm/°C is obtained experimentally in different linear operating intervals.