Portugal records third-warmest summer since 1931 as August rain eases drought

Third-warmest summer since records began in 1931

The summer of 2026 in mainland Portugal was the third warmest since official records began in 1931, according to the seasonal climatological bulletin published on 1 October 2026 by the Instituto Português do Mar e da Atmosfera (IPMA). The mean air temperature across the territory reached 23.17 °C, which is 1.21 °C above the 1991–2020 climatological normal. Only the summers of 2025 and 2005 recorded higher overall mean temperatures. The average maximum temperature reached 30.19 °C, ranking as the fifth highest on record, while the average minimum temperature stood at 16.15 °C, the sixth highest since 1931. All three summer months registered above-normal average temperatures, with the largest thermal deviations occurring in June.

Heatwaves and atmospheric dynamics

Atmospheric circulation during the season was shaped by a positive geopotential anomaly over Western Europe, including France, Italy, Spain, and the British Isles. Persistent anticyclonic conditions combined with hot air masses originating in North Africa to generate heat domes, high-pressure phenomena that trap and compress heated air over the region. Across Western Europe, areas in France and the United Kingdom recorded anomalies exceeding 4 °C above normal levels. In Portugal, these dynamics triggered two separate heatwaves: the first ran from 9 to 24 June, and the second lasted from 29 June to 11 July. The second heatwave became the third longest national episode on record, trailing only events in 1990 and 2020, and extended across 77% of analyzed weather stations.

Temperature records across mainland districts

Meteorological stations across the country registered 23 new high temperature extremes during the three-month period. The highest single temperature of the summer occurred on 3 July in Mora, located in the Évora district, where the mercury reached 44.3 °C. Conversely, the lowest minimum temperature of the season was recorded on 5 June in Lamas de Mouro, in the Viana do Castelo district, where temperatures dropped to 2.2 °C. The warmest day of the summer across mainland Portugal occurred on 4 July, when the daily mean of maximum and minimum temperatures averaged 29.31 °C nationwide.

Late August rainfall relieves drought conditions

Total seasonal precipitation across mainland Portugal reached 43.3 millimetres, representing 97% of the normal value and classifying overall summer rainfall as normal. Deficits during June and July were balanced by an unusually wet August, which recorded 260% of its normal monthly rainfall. Between 23 and 28 August, intense downpours affected the Lisbon region, the Tagus valley, and the coastline between Setúbal and Sines. Weather stations recorded 17 new daily precipitation records, with the highest 24-hour total reaching 58.2 millimetres in Vila Nova de Cerveira on 27 August. The late precipitation eased meteorological drought across the country. At the conclusion of the summer, 29.5% of mainland territory was classified as normal, 54.1% was in weak drought, 9.2% in moderate drought, and 7.2% in severe drought.