We report the thermal spin injection and accumulation in crystalline CoFe/MgO tunnel contacts to n-type Si through Seebeck spin tunneling (SST). With the Joule heating (laser heating) of Si (CoFe), the thermally induced spin accumulation is detected by means of the Hanle effect for both polarities of the temperature gradient across the tunnel contact. The magnitude of the thermal spin signal scales linearly with the heating power, and its sign is reversed as we invert the temperature gradient, demonstrating the major features of SST and thermal spin accumulation. Based on a quantitative comparison of the thermal and electrical spin signals, the thermal spin injection through SST is suggested as an effective route to inject the spin accumulation. (C) 2013 AIP Publishing LLC.