In order to predict metamorphic conditions near the slab/mantle-wedge interface and possible melting relations beneath the volcanic arc in southern Alaska, we have constructed a two-dimensional kinematic thermal model of the southern Alaska subduction zone that includes an abrupt change in slab dip at 40-km depth, time-dependent convergence rate, and variable shear heating. The numerical results indicate that the shallow-dipping slab segment in the southern Alaska subduction zone increases slab-surface temperatures up to 180 ¿C at depths <40 km and up to 90 ¿C at greater depths. Shear heating may increase slab-surface temperatures an additional 140 ¿C at depths <40 km and 70 ¿C at greater depths. Calculated pressure-temperature (PT) paths indicate that oceanic crust subducting beneath the southern Alaska forearc is undergoing blueschist-facies metamorphism. Calculated slab PT paths do not intersect the wet basaltic solidus for shear stresses ≤10% lithostatic pressure, suggesting that observed arc magmas are not derived from partial melting of subducting oceanic crust. The mantle wedge adjacent to the subducting slab lies at subsolidus conditions, and at depths <75 km, numerous hydrous phases are stable including serpentine, talc, amphibole, and chlorite. Low P wave velocities observed in the mantle wedge adjacent to the subducting slab probably reflect extensive hydration of mantle-wedge peridotite caused by fluids liberated from the subducting oceanic crust and sediments. Calculated PT conditions in the core of the mantle wedge permit partial melting if H2O is present either as a free fluid phase or fixed in amphibole. ¿ American Geophysical Union 1995