A method for the automatic design of an electronic circuit includes operations for evaluation of the thermal effects in the electronic circuit. The method generates a layout of the electronic circuit. Abstract data at the substrate level associated to the layout of the electronic circuit is then generated. A grid of partitioning is generated with respect to a view regarding the aforesaid abstract into meshes and nodes. The grid is applied to the substrate. On the basis of the grid (TG), a list of nodes or netlist representing a thermal network that represents the thermal behavior of the substrate or of its portions or elements is extracted. The netlist is useful in simulation operations, in particular of a SPICE type, for making an evaluation of thermal effects in the electronic circuit.