\citet{WangChunzai_2014} have shown that there is a global scale cold northern hemisphere--warm southern hemisphere bias common to the CMIP5 coupled models, which they propose is linked to the Atlantic Meridional overturning circulation being too weak. Consistently, in an observational and modeling study, \citet{Kang_2014} found that the Atlantic overturning was indeed responsible for the northern hemisphere being warmer than the southern hemisphere. The cold north and warm south SST bias over the Indian Ocean dominant during December--May found in our study seems to be a local manifestation of this global scale bias and can explain the drier long rains season over East Africa in coupled models. However, during June--November, the north-south asymmetry over the Indian Ocean is replaced by a west-east contrast: warmer--than--observed SSTs in the west and colder--than--observed SSTs in the east. These SST biases in the MRI-CGCM3 coupled model greatly increases rainfall over East Africa and can explain the wet bias during the short rains season. The mechanism behind the warm west and cold east asymmetry might be linked to the unrealistic mean thermocline slope tilting upward toward the eastern Indian Ocean as pointed out in \cite{Cai_2013}, who used it to explain the larger amplitude of the Indian Ocean Dipole (IOD) in CMIP3/5 models. However, what ultimately causes the thermocline bias and the detailed processes that develop the bias are less clear and will be explored in the future.