A nonlinear theory of a driven, inhomogeneous, one‐dimensional plasma of arbitrary temperature is presented. The model is solved numerically and analytically and detailed expressions are given for the saturated electric field excited at critical density. The results of the calculation are valid for arbitrary temperature and connect in a continuous manner the limits of cold wavebreaking and linear convective saturation. Comparison of the results of the calculation with particle simulations is made and good agreement is obtained.