  The nonlinear evolution of matter clustering induces temperature anisotropies
in the cosmic microwave background. The fluctuations in temperature are
produced at a relatively low redshift, $z\simlt 10$, and consequently are not
affected by the uncertain reionization proccesses that occurred at earlier
epochs. The amplitude of the effect depends on the evolution model assumed for
galaxy clustering. For plausible parameter choices, the temperature
fluctuations are in the range $10^{-6}\simlt \Delta T/T \simlt 10^{-5}.$
Observed limits on $\Delta T/T $ would be violated if nonlinear clustering on
present cluster scales commenced prior to $z\sim 10.$
