A method and apparatus for modeling and thermal analysis of semiconductor chip designs is provided. One embodiment of a novel method for performing thermal testing of a semiconductor chip design includes calculating full-chip temperatures over the semiconductor chip design (e.g., to identify steep thermal gradients) and modeling the full-chip temperatures in accordance with a geometric multi-grid technique. The geometric multi-grid technique is tailored to determine temperatures within the semiconductor chip design based at least in part on the physical attributes or geometry of the design.