Annual surface air and sub-sea water temperature data for a region are selected to approximate the geothermal gradient derived from the acquired deep borehole (>1000 m) temperature data. In mapping the geothermal gradient, weather stations and buoys are often not spatially co-located with boreholes. Furthermore, in prior works, the surface temperature averaged over Israel and its offshore region was used in geothermal studies. It is necessary, however, to consider using “borehole versus the nearest weather and surface temperature” values for geothermal applications. In our study, gridded average annual surface temperature data from weather stations and buoys were obtained and interpolated to borehole locations. A new geothermal gradient map is generated and evaluated against the prior map. It was found that areas with higher or lower annual temperature data, relative to the original value, alter the geothermal gradient and subsequent anomalies. In a prior work (Kahn, 2024), the preliminary regional geothermal gradient of Israel was mapped. Geothermal gradient data, together with additional application-related calculations, can be used to generate maps of geothermal energy resources, correlating oil and gas trends, carbon sequestration, bioremediation, and civil engineering. The improved annual surface temperature data sets create a segue for the depth estimation value precision.