Absolute MR thermometry has been unachievable clinically since the advent of MR and MR practitioners mostly rely on relative measurement of thermal changes using the proton resonance frequency shift method. Here, we introduce the JAMS method for reconstruction of absolute temperature using multinuclear frequency measurements. The method takes advantage of different frequency shifts with temperature of different nuclei (e.g. proton and sodium) for the reconstruction. Theory of the method is presented and proof-of-principle experiments validating the approach.