Background and aimThe increasing frequency of heat waves worldwide is a major challenge for emergency care providers worldwide. The aim of this study was to analyze the clinical features, treatment options, and early outcomes of heat stroke patients presenting to a large academic emergency department (ED) in Hungary and to provide guidance in management for other emergency professionals.MethodsPatients presenting to the ED between June 1, 2024, and July 31, 2024, with a body temperature above 40 °C were analyzed in a retrospective cohort study. Data collection included demographic, clinical and laboratory parameters. Predictors of mortality were analyzed with Mann-Whitney U test.ResultsEight patients were included in our analysis. Three patients died in the ED (37.5%). Patients who died had significantly lower pH (7.07 vs. 7.4, p = 0.036), higher potassium (7.3 vs. 3.2 mmol/L, p = 0.036), higher calcium (1.19 vs. 0.97 mmol/L, p = 0.036), higher lactate (10.9 vs. 3.5 mmol/L, p = 0.036) and higher PaCO2 (57.2 vs. 28 mmHg, p = 0.036) at admission compared to those who did not die.ConclusionsThe risk of heat stroke due to climate change-induced heat stress and the consequent thermoregulatory disruption may now be significant in temperate climate zones where it was not previously present. Standardization of differential diagnostic and therapeutic procedures could reduce mortality. pH, potassium, lactate and calcium levels may play an important role in predicting the outcome of heat stroke.