The Instituto Português do Mar e da Atmosfera (IPMA) confirms that Portugal is entering a volatile weather pattern, with extreme heat and strong winds return across the country. Following a period of elevated temperatures, a severe heat wave is forecast to intensify through the weekend of Saturday, 20 September 2026, with thermometers climbing toward 38°C in interior regions.
Key Takeaways:
• Heat Wave Warning: A six-day heat wave is highly probable starting Saturday, 20 September 2026, with maximum temperatures exceeding 38°C in Alentejo and Vale do Tejo — areas including Évora and Santarém that already recorded 38°C on Monday, 17 September.
• Wind Hazards: Gusts up to 75 km/h are expected along the western coastal strip and highlands through Friday, 19 September, posing risks to transport, agriculture, and outdoor infrastructure.
• Tropical Nights: Minimum temperatures will remain above 20°C in Alto Alentejo, Beira Baixa, and the leeward Algarve, preventing overnight cooling and increasing health risks.
A Meteorological Rollercoaster
Residents across mainland Portugal have experienced a week of intense, unseasonable heat. Contrary to earlier misrepresentations, Tuesday, 16 September did not bring a cooldown — instead, maximums remained above 30°C nationwide, with Évora hitting 38°C, Faro at 32°C, and other southern and central regions following closely. The cooling trend described in earlier reports was inaccurate; the heat has persisted, not receded.
Today, Thursday, 18 September, the IPMA confirms the continuation of strong winds — particularly between the Algarve and the northwestern coast — with gusts reaching 70 km/h during afternoon peaks. Lisbon is experiencing temperatures between 21°C and 35°C, with the afternoon heat rapidly intensifying.
The Azores High Flexes Its Muscle
From Friday, 19 September onward, the weather narrative sharpens. An anticyclone positioned north of the Azores has extended a ridge toward the Iberian Peninsula, effectively channeling a mass of hot, dry continental air over Portugal. This system is not a temporary fluctuation — it is a defining feature of the ongoing heat event.
By Saturday, 20 September, maximum temperatures will surpass 30°C across nearly all mainland territory, with Lisbon reaching 36°C. Sunday, 21 September, sees further escalation: the capital may approach 37°C, while Alentejo and Vale do Tejo are forecast to hit 38–39°C — levels consistent with peak summer conditions and far above historical means for late September.
Defining the Heat Wave
Portugal’s meteorological authority defines a heat wave as a period when maximum temperatures exceed the 30-year average (1991–2020) by 5°C or more for at least six consecutive days. Current projections confirm this threshold is already crossed, beginning on Monday, 17 September — marking one of the most prolonged and intense late-season heat events in recent history.
September 2026 is already trending 2.9°C warmer than normal, continuing an alarming pattern observed since early 2026. On 17 September — the day before this report — Portugal recorded its fourth-hottest September day since 1941, with a national average of 28.1°C. This reflects not an anomaly, but a new climatic norm.
What This Means for Residents
The combination of persistent heat and strong winds creates urgent, overlapping risks:
Urban dwellers in Lisbon, Porto, and Coimbra must prepare for continuous discomfort. Nighttime temperatures holding above 20°C leave no relief — especially dangerous for elderly and medically vulnerable populations. Keep blinds closed during the day; ventilate only after sunset.
Coastal visitors and fishermen should avoid sea activities through Friday. The western coastline from Cape Raso to the Alentejo coast will experience winds of 30–75 km/h, creating dangerous wave conditions. Even normally sheltered bays near the Algarve may see unexpected southerly gusts.
Agricultural workers and landowners are under acute pressure. Strong winds threaten irrigation infrastructure, greenhouses, and power lines. The Alentejo’s low humidity and parched soil — already in drought — now face critical fire risk. Authorities urge farmers to secure equipment and review emergency protocols.
Transport operators must exercise extreme caution. Gusts exceeding 70 km/h have historically destabilized high-riding trucks on highways like the A2, A6, and bridges near the Douro. Maritime routes along the Atlantic are also likely to face delays.
Looking Ahead
The IPMA indicates no precipitation is expected for the remainder of September. This reflects a broader, long-term shift: the Azores anticyclone has expanded to unprecedented levels over the past 1,200 years, particularly in summer and autumn, driving extended dry periods across Iberia.
While September 2025 was among the coolest starts to the century in Portugal, that was an outlier. In 2026, consistency is the new normal. Summer, in effect, refuses to end. Residents are advised to stay hydrated, check on vulnerable neighbors, and monitor IPMA alerts daily. The heat wave is not ending — it is deepening, and preparation is essential.
