Three of the SEASAT scanning multichannel microwave radiometer's (SMMR's) five frequencies can be used to determine the total precipitable water in the atmosphere, the liquid water content, and the rainfall rate. In addition, two distinct algorithms were used to derive geophysical parameters from brightness temperature. Comparisons with surface observations from the Gulf of Alaska SEASAT Experiment and other selected sources were made for both algorithms. Generally, very good agreement was found between satellite and radiosonde observations of total precipitable water. An estimate of the precision of radiosonde-derived total precipitable water amounts was made. Comparisons of precipitation occurrence as determined from the SMMR and surface observations also were made. In the tropics, very good agreement is found between satellite and surface observations. In the mid-latitudes (Gulf of Alaska) it is found that small cells of precipitation are often missed by the SMMR but larger synoptic scale scale precipitation is detected.