Breaking the link: Warming disrupts early-season rainfall predictability in the Caribbean

Sea surface temperatures (SSTs) in the tropical North Atlantic have historically served as reliable predictors of early-season rainfall across the Caribbean. In particular, rainfall onset has been linked to SSTs exceeding a convective threshold necessary to support deep convection. However, recent warming trends have altered this relationship. Here we show that despite SSTs now routinely surpassing the convective threshold earlier in the season, early rainfall has not increased. This decoupling reflects a shift in the atmospheric state: enhanced stability, evidenced by reduced convective available potential energy and increased convec-tive inhibition, is increasingly suppressing convection. In parallel, the Caribbean Low-Level Jet (CLLJ) has intensified, further inhibiting rainfall by promoting subsidence and the advection of dry air. Running correlations indicate that dynamic atmospheric variables now explain a larger share of rainfall variability than SST magnitude. These findings signal a regime shift in Caribbean rainfall dynamics and raise concerns about the declining utility of SST-based predic-tors under continued climate warming. The results have significant implications for seasonal forecasting and adaptation planning across Caribbean Small Island Developing States.