5G cellular systems will have the ability to communicate in either centimeter-wave or millimeter-wave bands, though not necessarily in both bands simultaneously. Therefore, techniques to optimize switching between those bands are needed. In this letter, we propose a suitable scheme based on rate prediction. Specifically, in each time-frame the base-station predicts the state of large-scale fading for the next time-frame; data transmission is then carried over the band that is anticipated to achieve the larger data rate. We analyze the scheme based on the assumption that large-scale fading is lognormally distributed and with a finite correlation between the two bands.