Portugal Heatwave: Temperatures Set to Reach 40°C Starting Saturday

Temperatures in mainland Portugal are expected to rise starting Saturday, June 20, with maximums likely to reach or exceed 40 degrees Celsius in several regions. According to Maria João Frada, a meteorologist at the Portuguese Institute for the Sea and Atmosphere (IPMA), these high temperatures may persist through a significant portion of next week.

The IPMA may issue heat warnings for various districts this weekend. These warnings could gradually expand to cover all of mainland Portugal starting Monday, according to Frada.

Early next week, temperatures are expected to range between 35 and 40 degrees Celsius. Frada noted that the 40-degree peaks will likely be confined to interior regions, specifically the interior of Alentejo, Vale do Tejo, and Vale do Douro. The western coastal strip may reach 35 degrees Celsius.

Why are temperatures rising in Portugal?

The current heat is caused by the transport of an air mass from North Africa and the interior of the Iberian Peninsula. This mass is being moved by a depression extending from North Africa to the Iberian Peninsula, according to Maria João Frada.

Frada stated that while these temperatures are above the average, they are common for this time of year. Minimum temperatures are also expected to rise across much of the territory, potentially leading to “tropical nights” with temperatures around 20 degrees Celsius.

Did You Know? The hottest days ever recorded in June for mainland Portugal occurred on June 17, 2017, and June 29, 2025, with some stations in Alentejo and Vale do Tejo exceeding 45 degrees Celsius.

What are the risks and historical implications?

The IPMA stated that this hot weather will increase the danger of rural fires. This elevated risk is expected to last at least until the middle of next week.

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The institute highlighted significant uncertainty regarding the exact intensity, duration, and geographical distribution of the upcoming episode. However, the current scenario shows consistency in meteorological models, according to Frada.

Expert Insight: Samantha Carter notes that the arrival of North African air masses creates a critical window of vulnerability for rural areas. The primary stake here is the intersection of high-temperature peaks with dry conditions, which directly accelerates fire volatility across the interior valleys.

What happens next with the summer forecast?

Sunday marks the official start of summer. Forecasts for that day indicate temperatures between 31 and 36 degrees Celsius across most of the territory, though interior Alentejo, Vale do Tejo, and Vale do Douro could again hit 40 degrees Celsius.

Some uncertainty remains for areas north of Cabo Raso. In the northern and central coastal strips, temperatures may remain below 35 degrees Celsius, according to Frada.

Frequently Asked Questions

When will the temperatures begin to rise?
Temperatures are expected to increase starting Saturday, June 20.

Which regions are most likely to hit 40 degrees Celsius?
The highest temperatures are expected in the interior of Alentejo, Vale do Tejo, and Vale do Douro.

What is the cause of this heatwave?
The heat is caused by an air mass from North Africa and the interior of the Iberian Peninsula transported by a depression.

How do you prepare your home and garden for extreme heat and fire risks?