Heat is preparing to return in force to mainland Portugal. A very hot air mass should settle over the Iberian Peninsula together with an anticyclonic configuration that favours atmospheric stability and additional warming. After a Wednesday still with temperatures relatively close to normal for September, thermometers begin to rise on Thursday, September 10, when some locations in the Lisbon and Setúbal districts could approach 30°C, and the warming will become more widespread from Friday onwards.
The most intense phase is forecast between September 12 and 15. The Tagus Valley, Ribatejo, Centro interior and Alentejo should concentrate some of the highest values. On Monday, September 14, maximums could reach 38°C in localities such as Coruche, Entroncamento, Golegã, Tomar and Abrantes, and 39°C in Mora and Ponte de Sor, in the Alentejo. In Centro, Vila Velha de Ródão could reach about 38°C and Castelo Branco 36°C. In the northern interior, Mirandela could reach 36°C, Amarante 37°C and Chaves 35°C.
In the Algarve, maritime influence should limit warming in coastal localities. For Monday, the forecast points to about 30°C in Faro, 31°C in Monchique and 33°C in Loulé, while in the Algarve interior Alcoutim could reach 36°C. Monday, September 14, should mark the peak of this episode, with the ECMWF and GFS models converging on a scenario of very high temperatures between Saturday and Tuesday.
The hot air mass could continue over the Iberian Peninsula until September 16 or 17. At about 1,500 metres altitude, thermal anomalies could reach approximately 8°C above normal in Portugal and exceed 10°C in other parts of the Iberian Peninsula. As this is a forecast several days in advance, the exact values may still change.
