Atmospheric stability sets maximum moist heat and convection in the midlatitudes.

Extreme near-surface moist heat and severe convective storms are among the leading causes of weather-related damages worldwide. Here, we show that episodes of extreme moist heat and severe convection frequently co-occur across midlatitude land regions and develop a theoretical framework that links their maximum intensities to preexisting low-level energy inversions in the atmosphere. By accounting for the stored-energy nature of midlatitude severe convection, where near-surface moist heat and atmospheric instability accumulate before convection initiates, our work advances the understanding of convective constraints on extreme heat events. The theory identifies low-level inversions as a critical factor shaping compound extreme heat and convective weather risks and offers a pathway for improving the modeling and future projection of these events and their co-occurrence.