Flight-averaged CCN concentrations during the Rain in Cumulus over the Ocean (RICO) field project varied by a factor of four. This was sufficient to provide correlations with flight-averaged total cloud droplet concentrations (N_c) and mean diameters (MD) that showed greater influence of CCN than updraft velocity (w) on N_c and especially MD. The product of CCN and w produced even stronger correlations with N_c and MD. An earlier RICO study had shown an inverse relationship of N_c and giant nuclei (GN) with large cloud droplet concentrations (N_LD). These two RICO studies now show that the aerosol with the most influence on N_LD (MD) is CCN. The results of the present study are similar to earlier studies in more polluted clouds that also showed more influence of CCN than GN on MD/N_LD/drizzle. The present study indicates that variations in CCN concentrations even within maritime air masses modulate precipitation.