This letter reports characterization and calibration of silicon microcantilever heaters for operation in liquid environments. Cantilever thermomechanical noise spectra were measured in air and in water using a commercial atomic force microscope. Cantilever electrical characteristics were measured in air and water. Laser Raman thermometry measured cantilever temperature in air and water, allowing temperature calibration through comparison with electrical characteristics. Cantilever thermal conductance in water was 136-610 W/K, depending upon the cantilever type. The cantilever electrical resistance is an accurate measure of cantilever temperature in both air and water.