The present paper is concerned with three-dimensional numerical simulations of hydrodynamics and convective heat transfer of a free surface liquid jet impinging onto a hot substrate. The Navier-Stokes equations for unsteady incompressible viscous fluids are used and are solved numerically by a finite difference method. The numerical model is validated by comparing the results with experiments conducted by other researchers under the conditions of normal impingement. Oblique impingement of liquid jets onto a substrate is treated. It is found that the stagnation point does not coincide with the geometric jet center on the solid surface. The deviation increases with decreasing impact angles, i.e. increasing degree of obliqueness. The peak of local Nusselt number is also shifted in accordance with the flow profile. The velocity and temperature distributions are examined in detail to better understand the physics of the oblique impingement phenomena.