Thermal models have been constructed to demonstrate how regional crustal deformation and subsequent asthenospheric upwelling associated with the migration of the Mendocino triple junction affect the thermal regime of the northern California Coast Ranges. Ephemeral crustal thickening caused by the migration of the triple junction, coupled with the thermal effects of inflow of asthenosphere into the slab window, produces a heat flow signature that is consistent with the observed surface heat flow in the region. In addition the thermal models provide evidence that slab window temperatures are lower than previously assumed following the passage of the triple junction.