Summer 2026 Was Mainland Portugal's Third Hottest Since 1931, With Record Warm Nights in Lisbon, Coimbra and Viana do Castelo

The summer of 2026 was the third hottest on mainland Portugal since records began in 1931, beaten only by 2025 and 2005, according to the seasonal climate bulletin published on Wednesday by the IPMA (Instituto Português do Mar e da Atmosfera, the national weather and sea institute).

The average air temperature from June to August was 23.17 °C, 1.21 °C above the 1991 to 2020 normal. Last summer's 23.51 °C remains the record, followed by 2005 at 23.43 °C. The IPMA classes the season as "very hot" for temperature and "normal" for rainfall, and notes that each of the last five summers has been warmer than average.

Hot days, and hotter nights

Average maximum temperatures, at 30.19 °C, were the fifth highest since 1931 and 1.5 °C above normal; the ten summers with the highest maximums have all come in the last 25 years. Average minimums, at 16.15 °C, were the sixth highest.

The nights stood out in the record books. Of the 23 new station records for high temperatures set this summer, 18 were for the minimum, and 13 of those fell in July. Five were all-time records for any month: at Lisboa/Tapada, Coimbra/Bencanta, Figueira da Foz, Viana do Castelo and Cabo Raso. Minimum temperatures stayed above the monthly average for 27 consecutive days, from 11 June to 7 July.

There were two heatwaves, from 9 to 24 June and from 29 June to 11 July; the second reached 77 percent of the stations analysed. The hottest day was 4 July, when the mainland's average daily maximum reached 38.3 °C. The highest single reading was 44.3 °C at Mora, in the Alentejo, on 3 July.

The warmth was not evenly spread. Torre de Moncorvo, in the upper Douro, ran 3.3 °C above its normal average, and Cabeceiras de Basto's maximums ran 4.3 °C above. Melgaço, at the northern tip of the country, was 2.3 °C cooler than usual, and Reguengos de Monsaraz was the hottest council on average, at 26.3 °C.

A wet August balanced the books

Rainfall totalled 43.3 mm across the three months, 97 percent of normal, but only because August brought 2.6 times its usual rain. June and July were both drier than average. All 17 new daily rainfall records came in August. The heaviest spell ran from 23 to 28 August, with rain and strong showers above all around Lisbon, the Tagus valley and the coast between Setúbal and Sines. The wettest day anywhere was 58.2 mm at Vila Nova de Cerveira on 27 August.

The coast and the interior had different summers. Some councils in the districts of Lisbon, Santarém and Setúbal received 150 to 200 percent of their normal rain, with Almada the highest at 207 percent. In the interior Alentejo and the eastern Algarve, some councils had less than a quarter of normal, and Olhão had just 8 percent (0.7 mm).

Drought persists in the south

By the end of August, the IPMA's drought index placed 29.5 percent of the mainland in the normal class, 54.1 percent in weak drought, 9.2 percent in moderate drought and 7.2 percent in severe drought. The north and centre-north are now almost entirely normal, but the Alentejo and the Algarve remain in meteorological drought, and the area of severe drought in the south-east grew over the summer.

The hot, dry June and July came in a fire season that ended with 74,267 hectares burnt, less than a third of 2025's total. For reservoir levels, which follow a different pattern from the rain, see our report on the northern basins running below their September average.