A prolonged heatwave lasted for 13 days, finally ending on the evening of 28 July 2025. This event stands out as one of the longest heatwaves ever recorded in Greece.
Strangely enough, the two longest heatwaves have both happened in the last three years. This seems to show a recent trend of extended extreme heat periods.
The temperature data came from a wide network of automatic weather stations. During the heatwave, several stations kept recording temperatures above what most would consider dangerously high.
You can break down the heatwave into two phases. The first phase ran from 14 to 17 July.
The second, and honestly more brutal, phase stretched from 20 to 28 July. Between these, there was a short break—just two days, 18 and 19 July—when things cooled off a bit and felt closer to normal for the season.
The heatwave peaked on 25 July, which became the hottest day of the month nationwide. Over 360 stations reported temperatures above 37°C, and about 167 locations faced even more severe heat above 40°C.
Almost everyone in the country felt temperatures above 40°C. That’s how widespread the impact was.
The data for both phases also highlights the top five highest temperatures recorded during each stretch. It gives a pretty vivid picture of just how extreme things got.
One reading at Skala Messinias really stood out—45.8°C. That’s only 0.6°C below the all-time record for the automatic weather station network, which was set at 46.4°C in the summer of 2023.
These exceptional temperatures hit several regions: Thessaly, the Peloponnese, Western Greece, Epirus, Eastern Central Greece, Macedonia, Thrace, and southern Crete. Folks in these areas got the worst of it, with the highest and most relentless heat.
Major urban areas really felt the heat, too. In parts of Attica, for example, temperatures stayed at or above 30°C for up to 80% of the total hours during the most intense nine-day stretch, from 20 to 28 July.
Even at night, the air stayed hot, barely cooling off at all. That made things tough for city infrastructure and residents just trying to get by.
The urban heat island effect probably made things worse. Cities trap heat and don’t cool down like rural areas after sunset.
This long exposure to high temperatures raised health risks, drove up energy use, and put extra pressure on water supplies in crowded places.
If you want to see how temperatures changed across time and region, here’s a summary table:
Phase |
Dates |
Key Characteristics |
Highest Temp (°C) |
Areas Impacted |
|---|---|---|---|---|
Phase 1 |
14–17 July |
Initial heat surge, rising temperatures |
Up to mid 40s |
Various regions starting heatwave conditions |
Transitional |
18–19 July |
Temperatures near seasonal norms |
Around 30 |
Cooling, temporary relief |
Phase 2 |
20–28 July |
Strongest, longest period with intense heat |
45.8 (Skala Messinias) |
Large parts of Greece, urban and rural areas |
Throughout this time, temperatures clearly ramped up again after the short break. The peak on 25 July really drove home just how widespread the phenomenon was.
The National Observatory of Athens ran the monitoring network that captured all this data. Their automated stations sent in constant temperature readings, so meteorologists could track real-time changes and send out alerts.
All this data helps us get a grip on how today’s heatwaves behave. It also helps us think about how to prepare for future events.
Sustained high temperatures, especially in cities, put extra pressure on everyone. It really makes you wonder if we need better urban planning and smarter cooling strategies.
If nights don’t cool off, heat stress just keeps building up, which leads to more hospital visits and, unfortunately, sometimes worse. For more details about the end of this heatwave and the highest temperatures recorded, check out the report on the conclusion of the 13-day heatwave.
