Using the Zimenkov-Ivanov model of hail melting in the atmosphere and modern data on the level of zero isotherm in Kakheti (Georgia), the critical size of hailstones in clouds that are not harmful to crops in the conditions of this region was estimated (almost complete melting of hailstones near the earth’s surface at altitudes 250, 500, 750 and 1000 m). The calculations were performed for the average ten-day values ​​of the heights of the zero isotherm from April to October. In particular, it was found that the critical size of hailstones in clouds, almost completely melting near the surface of the earth at an altitude of 1000 m and 250 m, respectively, varies from 0.73 to 0.92 cm for the first decade of April and from 1.43 to 1.60 cm for the second decade of August.