Western Europe just experienced its hottest June on record. The average temperature reached 20.74°C (69.33°F) — more than 3°C hotter than the normal temperature from 1991 to 2020 — according to the EU's Copernicus Climate Change Service Al Jazeera. Globally, June 2026 was the second-hottest June ever recorded Copernicus Climate Change Service.

The heat killed thousands of people. Authorities in France, Belgium, Spain, and the Netherlands have counted more than 4,700 excess deaths linked to the June heat as of July 9, up from 3,700 just two days earlier Reuters. In France alone, more than 1,200 people died on June 24, and over 1,400 died on each of June 25 and 26 Santé publique France. Older people were hit hardest.

The intense heat developed over several weeks. An unusually severe heatwave struck from May 21 to 30, with some areas running 10°C hotter than normal Copernicus. The pattern continued into June: Spain recorded its hottest June days ever on the 23rd and 24th WMO.

Temperatures soared past 40°C (104°F) in many places by June 22 Reuters. People died in cars, vehicles, and from drowning as they sought relief in water — drowning deaths in France jumped from about 40 on June 23 to at least 48 by June 24 Reuters Reuters. Power cuts made things worse, leaving people without air conditioning during the worst days. More than two-thirds of Europeans — about 410 million people — experienced temperatures above 35°C (95°F) at some point Al Jazeera.

What caused this? A heat dome — think of it like a heat lid sitting over Europe. A stationary high-pressure system blocked normal air circulation, trapping hot air in place like a cover on a boiling pot. This system also kept rain away and prevented nighttime temperatures from dropping. High humidity made the air feel even hotter and more dangerous. Normally, people and buildings get some relief at night when temperatures cool down. Not this time. The combination of extreme daytime heat and warm nights throughout the period is what made this event so deadly.

The oceans broke records too. Average sea surface temperature hit 20.86°C (69.55°F) in June, the highest ever measured for that month Al Jazeera. The Mediterranean experienced a marine heatwave. Warmer ocean water reduces the cooling effect that coastlines normally provide and harms sea life. Inland, dry conditions created drought risk in Eastern Europe and fed wildfires across Spain and southern France, stretching firefighting resources thin.

The death toll numbers will likely rise. These counts are always revised as data gets collected over time, which is why the jump from 3,700 to 4,700 deaths in two days is normal for how this kind of reporting works. What concerns experts more is that the World Health Organization warned Europe could face "more deadly weeks" as another heatwave builds Reuters. This suggests June was not a one-time event but the beginning of a longer hot season. Whether this becomes the new normal for European summers depends on what happens for the rest of the year and whether the early warning systems built after previous deadly heatwaves can handle longer periods of humid heat.