Catalonia registers 13 deaths associated with high temperatures in the two days before Saint John

BarcelonaThe heatwave hitting Catalonia has had a clear impact on health. In two days –Monday 22 and Tuesday 23 June– thirteen deaths associated with high temperatures have been recorded, coinciding with the peak of high temperatures, according to the Daily Mortality Monitoring System MoMo of the Carlos III Health Institute. This is the start of the summer season with the highest mortality since records began in 2015. Of the series, only June 2022 had a worse performance, with deaths before the first fortnight of a month that ended with 39 victims.

Of the thirteen deaths, eight are women. In both sexes, the majority of deaths attributable to the thermometer are people over 85 years old and none are under 45 years old. From this profile, it can be concluded that the deaths are not caused by heatstroke due to exposure to high temperatures or physical exertion, but rather that the victims likely already had a medical condition and the heat has destabilized or helped to deteriorate their vital functions. That is why it is so important for vulnerable people, especially the elderly and children, to hydrate well by drinking plenty of water.

Since MoMo collects daily mortality data, June 2026 presents itself as a month with high mortality in Catalonia, already doubling the total for most years. Of the historical cumulative, only June 2022 recorded deaths in the first half of the month. But June 2025 is the deadliest month so far, with 56 recorded deaths – the first of which occurred on June 22 –, compared to the 39 deaths in June 2022.

Catalonia's situation is the same in Spain, where a May was already recorded with 101 deaths, a figure that had never been reached at this point of the year and triples the average of the last decade. Until yesterday, the high temperatures, especially in the southwest of the Peninsula, had left 212 people dead.

The MoMo data is not a statistic but is calculated by cross-referencing daily death certificates with the predicted excess mortality and with records of maximum and minimum temperatures that occur.

In fact, heat stress due to high temperatures has intensified worldwide, and regions like the Mediterranean and South America are registering up to fifty additional days per year with severe to extreme heat stress compared to the 1970s. Research published in Nature Climate Change, led by the European Centre for Medium-Range Weather Forecasts, indicates that global heat stress is intensifying both day and night. The team analyzed a global dataset on human heat stress from 1950 to 2024 and found that perceived temperatures have increased on days and nights since the 1970s.

This is, therefore, a phenomenon that particularly affects nights. Data suggest that the ten warmest nights of each year have warmed more rapidly than the ten warmest days, at an average global rate of 0.32 degrees per decade, compared to 0.27 degrees per decade, respectively.