Temperature is of primary importance for many physical properties in the Martian soil. We measured diurnal and annual soil (and surface) temperature variations using the NASA InSight Mars mission’s HP3 radiometer and thermal probe. At the depth of the probe of 0.5 - 36 cm, an average temperature of 217.5K was found varying by 5.3 - 6.7 K during a sol and by 13.2K during the seasons. The damping of the surface temperature variations in the soil were used to derive a thermal diffusivity of 2.30±0.03×10−8 m2/s for the depth range of the diurnal wave - thermal skin depth 2.5±0.04 cm - and 3.74±0.61×10−8 m2/s for that of the annual wave, with a thermal skin depth of 84±10 cm. The temperatures measured are conducive to the deliquesence of thin films of brines in the soil. These are of astrobiological interest and may explain the formation of the observed cemented duricrust.