  In this research, the Cauchy problem of the 3D viscous Boussinesq system is
studied considering an initial temperature with negative Sobolev regularity.
Precisely, we construct local in time mild solutions to this system where the
temperature term belongs to Sobolev spaces of negative order. Our main
contribution is to show how the coupled structure of the Boussinesq system
allows us to considerably weaken the regularity in the temperature term.
