Abstract Quantitative proxy records of past temperatures remain critically missing in northern Mexico. Here we present a new record of terrestrial temperature, hydroclimate, and vegetation variability during Dansgaard‐Oeschger (DO) Event 22, a millennial‐scale warming event, using a stalagmite from northern Mexico. We apply nucleation‐assisted fluid inclusion microthermometry to obtain highly precise temperature measurements (Th∞), integrating these with stable isotope (δ18O, δ13C) and trace element (Mg/Ca, Sr/Ca) analyses. Our results reveal significant warming of 2.3°C–2.6°C during DO Event 22, coincident with increased moisture availability and increased soil/vegetation activity. These findings are coherent with regional and global records, emphasizing the impact of ocean circulation and associated abrupt global temperature changes on Mexico’s climate. This study represents the first stalagmite‐based reconstruction in Mexico to comprehensively link terrestrial temperature, hydroclimate, and vegetation dynamics, providing a crucial framework for understanding past climate variability and improving assessments of warming impacts.