[en] In this study, we analyzed phosphorescence lifetime and its accuracy by growing frost for thermographic phosphor thermometry in a low-temperature environment. Mg₄FGeO₆:Mn particles were coated on an aluminum plate and excited with a UV-LED to obtain phosphorescence signals. The surface temperature was maintained at  −20, −15, −10 °C, and the phosphorescence signal was acquired as the frost grew for 3700 s. The lifetime was calculated and compared with the calibration curve under no-frost conditions. The error of the measured lifetime was within 0.7% of that in the no-frost conditions. A 2D surface temperature profile of the target plate was successfully obtained with the frost formation. (paper)