Taking the local weather in Mercedes Sur into account is an important factor for planning your visit, especially if you plan to spend your trip by the pool. The hottest months are usually March and April, with an average temperature of 28°C, while the coldest months are January and December, with an average of 27°C. The rainiest months in Mercedes Sur are October, August, November and July, with each month seeing an average of 1003 mm of rainfall.