The variations with the seasonal cycle of the atmospheric response to constant SST anomalies in the eastern tropical Pacific are investigated with the atmospheric GCM, HadAM3. The equatorial wind response is weakest in January and February when the warmest SSTs are south of the Equator and strongest in April when the warmest SSTs are on the Equator. This may have consequences for the seasonality of the onset and termination of El Ni¿o. Westerly wind anomalies in the tropical Pacific associated with El Ni¿o have previously been observed to shift south of the Equator, weakening on the Equator, during the northern winter. It has been suggested that this may contribute to the termination of El Ni¿o in spring. These experiments demonstrate that such a shift can arise solely in response to the mean seasonal cycle during El Ni¿o and does not require changes in SST anomalies.