Three Summer Heat Spells Left an Estimated 680 Excess Deaths in Portugal, INSA Finds
The National Health Institute links three 2026 heat episodes — 16 June, 2–8 July and 23 July — to about 680 more deaths than expected, most among people aged 75 and over. Officials say public warnings and precautions kept the toll below what forecasting models had predicted.
Portugal's summer heat carried a measurable human cost this year. The National Health Institute Doctor Ricardo Jorge (Instituto Nacional de Saúde Doutor Ricardo Jorge, or INSA) estimates that three distinct hot spells between mid-June and late July were associated with about 680 more deaths than would normally have been expected — a sobering tally that puts numbers to a season most residents felt mainly as discomfort.
The institute breaks the toll into three episodes. A single very hot day on 16 June was linked to 62 excess deaths, some 22% above the expected level. By far the deadliest stretch was the week of 2 to 8 July, when a prolonged heatwave was associated with roughly 555 excess deaths, about 29% more than normal. A further short burst of heat around 23 July added an estimated 63 deaths, again some 24% above the baseline. Excess mortality of this kind is calculated by comparing the deaths recorded during an event with the number statisticians would expect for the same dates in an ordinary year.
The burden fell overwhelmingly on the oldest residents. The great majority of the additional deaths were among people aged 75 and over, and the causes were dominated by circulatory and respiratory conditions and by cancer. Heat rarely appears on a death certificate as the sole cause; instead it acts as a trigger or an aggravating factor, tipping already-fragile patients over the edge. That is why the very old and the chronically ill bear the brunt, and why the elderly living alone are the group public-health officials worry about most.
Health authorities were keen to stress that the outcome could have been worse. Officials said the protective measures deployed during the heatwaves — public warnings, guidance to stay hydrated and out of the midday sun, and closer attention to vulnerable groups — appear to have kept the death toll below what forecasting models had predicted. The figures, in other words, describe a serious but partly mitigated event rather than an unchecked one.
The estimate is the product of Portugal's summer surveillance system, in which INSA works alongside the Directorate-General of Health (Direção-Geral da Saúde, or DGS) and the Portuguese Institute for Sea and Atmosphere (Instituto Português do Mar e da Atmosfera, or IPMA), the national weather service, to track temperatures and mortality in near real time. When forecasts point to dangerous heat, the system triggers alerts and contingency plans across the health service.
For a country that markets its climate as one of its greatest assets, the data are a pointed reminder that hot summers are also a public-health challenge, and an intensifying one. Heatwaves are becoming more frequent and more severe across southern Europe, and the populations most exposed — the elderly, the isolated, those with chronic illness — are exactly the groups expanding as the country ages. For residents, the practical lessons are unglamorous but effective: check on older neighbours and relatives during hot spells, keep homes cool and hydration up, and take the IPMA's warnings seriously. This summer's 680 excess deaths are a statistic; behind each one, the season's heat was a factor that the right precautions can help blunt.
