Recently, different transport coefficients have been measured in high-T-c superconductors to pinpoint the nature of the pseudogap phase. In particular, the thermoelectric coefficients received considerable attention both theoretically and experimentally. We numerically simulate the Nernst effect in extreme type-II superconductors using the time-dependent Ginzburg-Landau equations. We report the sign reversal of the thermoelectric coefficient alpha(xy) at temperatures close to the mean-field transition temperature T-c(MF) (H), which qualitatively agrees with recent experiments on high-T-c materials. We also discuss the noise power spectrum of alpha(xy), which shows 1/f(beta) behavior. Based on this observation, we propose an experiment to distinguish among different regimes of vortex dynamics by measuring the noise correlations of the Nernst signal.