As already well known, Terna leads the Working Package 5 of The Italian demo of the H2020 Osmose project, which stands for Optimal System-Mix Of flexibility Solutions for European electricity. The main purpose of OSMOSE is developing a novel Energy Management System (EMS), which allows managing distributed Renewable Energy Sources (RES) and grid congestions, by properly coordinating innovative flexibility resources which include Dynamic Thermal Rating (DTR) and Demand Side Response (DSR). In this innovative approach, one of the two DTR investigated methods, which have been both developed by Ensiel, a consortium of Italian universities active in power systems research, is the Weather Based DTR. This technique is based on a thermo-mechanical model of the monitored line and on a detailed weather forecast of the involved area, having as final output the loadability curve of the line. The main features of the Weather Based DTR solution are described in this paper, and the first experimental results obtained on real case studies are presented and discussed in order to prove their effectiveness.