The Portuguese Institute for Sea and Atmosphere (IPMA) has issued a red alert, with the source noted in Portuguese, warning Lisbon and Setúbal from midnight Thursday until the end of Friday due to persistent extreme temperatures, both maximum and minimum.
Coimbra and Leiria will also be placed under a red warning, the highest level indicating an extreme weather risk, on both Friday and Saturday as hot, dry conditions persist.
Castelo Branco, Portalegre, Évora and Beja have been under an orange warning since Wednesday, the second‑highest risk category, and this will be extended to the entire mainland on Friday.
Maximum temperatures are forecast to exceed 35 °C nationwide, with values above 40 °C in inland and southern regions and the possibility of reaching 43 °C in Alentejo through next Monday.
Minimum temperatures will stay above 20 °C across much of the mainland, and in several areas they may remain between 24 °C and 28 °C for multiple nights, including Greater Lisbon.
The IPMA predicts that this extreme heat episode will persist for at least one week.
In a statement, the Portuguese meteorological institute notes that, compared with the usual mainland climate, the situation will be particularly unusual in coastal areas, where limited sea‑breeze penetration or weak intensity will keep high temperatures for consecutive days, creating a rare scenario.
The weather conditions in mainland Portugal are being driven by an anticyclone positioned to the north‑northwest of the Azores archipelago.
Very high to extreme ultraviolet levels in the coming days
The IPMA warns that the forthcoming hot weather will produce very high to extreme Ultraviolet Index values across the mainland.
Consequently, through Friday 3 July, all districts are expected to experience very high UV Index levels, ranging from 10 (very high) up to 11 (extreme).
The institute advises avoiding sun exposure around solar noon, when the UV Index peaks.
Solar noon in mainland Portugal occurs around 1:30 pm, varying slightly with latitude and gradually shifting later from north to south, according to the IPMA. The institute recommends minimizing sun exposure between 11 am and 4 pm, and using UV‑filtered sunglasses, a hat, a T‑shirt, a parasol and sunscreen.
