Journal Article

Contributions of Atmospheric Ridging and Low Soil Moisture to the Record‐Breaking June 2023 Mexico‐Texas Heatwave

Ting, Mingfang, Kalashnikov, Dmitri A., Cook, Benjamin I., Singh, Deepti

2025

Overview

June 2023 witnessed the hottest, largest, and longest‐lasting heatwave across Mexico and Texas between 1940 and 2023. We apply constructed analogs with multiple linear regression models to quantify the contribution of different drivers to daily temperature anomalies during this heatwave. On the hottest day (20 June), circulation, soil moisture, and their interaction explained 3.82°C (90% CI: 2.72–4.91°C) of the 5.42°C observed anomaly with most of the residual attributed to the thermodynamic effects of long‐term warming. Using CESM2‐LENS2, we find that June 2023‐like patterns are not projected to increase in frequency but will become 1.9°C hotter by the mid‐21st century under SSP3‐7.0. The hottest simulated day with these patterns could produce temperatures >50°C (122°F) across south Texas, representing a low‐likelihood yet physically plausible worst‐case scenario that could inform disaster preparedness and adaptation planning. Plain Language Summary During summer 2023, multiple heat waves affected Mexico and Texas and contributed to hundreds of heat‐related fatalities and thousands of heat‐related emergency‐room visits. Particularly notable was an unusually intense and persistent early‐season heat wave in June, when numerous locations exceeded their all‐time record highs. This heatwave was the hottest, largest, and longest‐lasting heatwave to affect the Mexico‐Texas region in the observational record spanning 1940–2023. In this study, we quantify the influence of atmospheric circulation and soil moisture on the heatwave intensity. We find that these factors together account for most of the extreme temperature anomaly at the peak of the heatwave, with most of the remainder explained by long‐term warming. We also find that June 2023‐like circulation patterns will not occur more frequently but are projected to become nearly 2°C hotter than present by the mid‐21st century. The hottest simulated day with these patterns could produce widespread temperatures hotter than 50°C (122°F) across south Texas. Although these temperatures have a low probability of occurrence, they represent physically plausible conditions that could threaten human survivability. Such low‐likelihood, yet high‐risk scenarios can inform disaster preparedness and adaptation planning efforts. Key Points A heatwave with record‐breaking intensity, persistence, and spatial extent affected Mexico and Texas during June 2023 Circulation, record‐low soil moisture, and their interaction explain most of the temperature anomaly at peak of heatwave June 2023‐like patterns are projected to warm an additional 1.9°C by the mid‐21st century due to regional warming and drying

• Publisher: John Wiley & Sons, Inc,Wiley
• Subject: 21st century / Adaptation / Analogs / Atmospheric circulation / attribution / Circulation patterns / constructed analogs / Daily temperatures / Disasters / Emergency preparedness / extreme heat / Heat / Heat waves / Mexico / Moisture content / Regression analysis / Regression models / Ridging / Soil / Soil moisture / Statistical analysis / Survivability / Temperature anomalies / Temperature extremes / Texas