Portugal braces for 40°C heatwave as Santo António festivities begin

A mass of hot, dry air from North Africa will push temperatures in Portugal to 40°C over the coming days, coinciding with the peak of the Santo António festivities. The national weather office, IPMA, has issued yellow heat warnings for all mainland districts, and civil protection authorities warn of maximum fire risk.

Heatwave timing and warnings

The heat will build sharply on Thursday, 11 June, when temperatures in some areas could climb 10°C above previous levels. On that day, yellow warnings apply to 15 of Portugal's 18 mainland districts—only the northern interior regions of Bragança, Vila Real and Viseu initially escape the alert. By Friday, the warnings extend to every district as the mercury peaks. IPMA expects Friday to be the hottest day, with maximum temperatures ranging from 35°C to 40°C across most of the country. The interior, especially the Alentejo, Tagus Valley and central regions, will bear the brunt, with forecasts of 41°C in Portel and 40°C in several municipalities including Tomar, Évora and Alcácer do Sal. Only the southern Algarve coast may see maxima slightly below 30°C. Overnight lows will also be unusually warm, staying at or above 20°C in many places, and a drop in wind speed will make the heat feel more oppressive. On Saturday, the heat persists, but cloudier skies and thunderstorms—possibly intense and accompanied by hail—could develop over inland areas, particularly in the North and Centre and up to Alto Alentejo.

Fire and health risks

The prolonged hot spell has put authorities on high alert for rural fires. The National Emergency and Civil Protection Authority (ANEPC) warned that conditions pose a “very high or maximum” fire danger and urged the public to avoid any open flames, including burnings, campfires and smoking in forested areas. Lisbon’s municipal civil protection service raised the fire risk to its maximum level from 11 June, citing the IPMA yellow warning that forecasts a maximum of 36°C in the district. The heat also poses direct health risks, especially for vulnerable groups such as young children, the elderly, people with chronic illnesses and those experiencing homelessness. Authorities advised staying hydrated, seeking cool environments and limiting sun exposure during the hottest hours.

Climate backdrop

The heatwave follows a May that was the second-warmest globally on record, according to the Copernicus Climate Change Service. Portugal itself set 25 new maximum temperature records for May, including 40.3°C in Mora, and endured a heatwave lasting 9.5 days—the second-longest for the month since records began, exceeded only by a 9.7-day event in 1964. While the current episode is linked to a hot air mass from North Africa, it also coincides with emerging signs of an El Niño event, with subsurface waters in the tropical Pacific showing temperature anomalies above +6°C. IPMA notes that El Niño’s influence on Portugal is indirect but could affect precipitation and air temperature patterns over the Iberian Peninsula, particularly during the Northern Hemisphere winter.

Cooling relief ahead

The extreme heat will not last long. IPMA forecasts a sharp drop in maximum temperatures from Sunday, 14 June, and into Monday, though summer-like conditions are expected to persist across much of the country through the following week. The weekend’s storms may also bring a temporary respite, but for now, Portugal is set to swelter through its hottest days of the year so far.