This work explores the interaction between the Urban Heat Island (UHI) and the sea breeze interaction on a severe weather episode that occurred in February 01, 2003 in the Metropolitan Area of São Paulo. The work was developed through numerical modeling of the atmosphere using the Regional Atmospheric Modeling System (RAMS) with high spatial resolution and with a physically appropriate parameterization for urban areas (TEB). A factor separation method, which allows the identification of individual contribution of each factor and their interaction on a specific meteorological field, was used in order to identify the contributions of the UHI and the sea surface temperature (SST) to the event. The results show that UHI positively contributes to the total precipitation occurred during the event and that this contribution is dependent on SST, with distinct responses to its increasing or decreasing. With an increase of 2ºC in the observed SST the UHI can cause an increase of 28% in the total accumulated precipitation in the grid domain. The same temperature increase in a situation that the SST is 2ºC colder results in an increase of 14% only.