Abstract Many regions worldwide, including Subtropical South America (SSA), face significant challenges from convective systems that produce severe weather. However, limited research exists on how these systems may change under future climate conditions. Using daily data from 50 simulations with the Community Earth System Model spanning 1870–2100, we study historical and future changes in large‐scale atmospheric parameters relevant to convection. Projections for austral spring and summer include an increase in convective available potential energy, convective inhibition, and vertical wind shear. Uncertainties in future projections arise from natural climate variability, which can either amplify or attenuate forced changes. Our findings suggest that future convective environments over SSA may be those that favor less frequent but more intense convection. Our study enhances understanding of the possible future nature of convective environments and emphasizes the importance of considering both the forced response and natural climate variability in climate change projections.