To decipher the thermal structure of the sedimentary veneer in southern Israel, new values of thermal conductivity and porosity as well as of the radiogenic heat budget are provided. Thermal conductivity is measured for lithotypes and scaled up for geological formations. The new data are higher than most of the previously measured values, in particular for sandstones and siltstones, whose mean values are 5.0 and 2.9 W m−1 K−1. Mean values of the most abundant lithotypes, which are dolomites and limestones, are on the order of 4.1 and 2.7 W m−1 K−1, respectively. The total radiogenic heat production of the sedimentary cover varies slightly over southern Israel, due to variable lithology and total sediment thickness, yielding a maximum heat flow on the order of 4 mW m−2 where the sedimentary section is thickest (ca. 7 km). A temperature prognosis was made by calculating temperature profiles to the top of the crystalline basement at five well locations applying the new thermal-conductivity data set and three scenarios of surface heat flow (50, 55 and 60 mW m−2). The calculated temperatures best match with measured drillstem-test temperatures by using heat-flow values close to the upper bound of range. Surface heat flow on the order of 55–60 mW m−2 is supported by a reevaluation of an existing temperature log and the application of thermal conductivity from this study. The temperature prediction for southern Israel shows values of 100–120°C at 3500–4500 m depth, indicating a geothermal potential that can be used for heating as well as electricity production.