A technique for measuring the temperature of rain at the ground and the methods for calibrating the equipment used for this purpose are described in this report. A preliminary analysis of the data indicates that significant differences between the rain and ambient air temperatures usually occur in the first portion of the thunderstorm rain period and that the differences in temperature between the ambient air and the rain falling from the latter portion of the storm are small. Abstract A technique for measuring the temperature of rain at the ground and the methods for calibrating the equipment used for this purpose are described in this report. A preliminary analysis of the data indicates that significant differences between the rain and ambient air temperatures usually occur in the first portion of the thunderstorm rain period and that the differences in temperature between the ambient air and the rain falling from the latter portion of the storm are small.