Do you live in Southern/Southeastern Europe (or otherwise close to the Mediterranean coast) by any chance? If not then where was this? Humidity and house design are the real killers here; I know a guy from a literal desert where summers mean whole months of 40C°+ peaks who now studies in Germany. When talking about the recent heat wave, he said and I quote: “I drank nothing but water for two days straight because anything I ate would warm me up.” You can’t rely on the temperature alone for this.